There is a society that is accustomed to magic but not everybody can use it. So the people without magic develop their own technology. Some of their tech relies on magic, some does not. The question:

How would technology develop differently if magic were present in the world?

Right now general terms are fine. I haven't defined all of the parameters for the magic as this is in its very early stages. I am thinking of something like an old west setting. Do guns change when mages have shield spells? Do the mages find different ways to use magic to defend against the tech?

I am thinking there may have been a period of time when those with and without magic were feuding and neither side would help the other. I believe this would result in a growth of tech.

Do you know of any books that approach a magic/tech world like this?

http://en.wikipedia.org/wiki/Arcanum:_Of_Steamworks_and_Magick_Obscura

You could have mage shields that stop high-velocity projectiles, so the teckies develop a gun that shoots force that crushes them instead.

think of something that we normally do, possibly with difficulty, that would be done easier with magic.
I have done several story ideas based on where there is no electricity or electricity had not been developed. One might have magic to cause the spark in the place of the spark plug so you can have cars.
One might have magic turn water into a fuel, or use magic to filter crude oil into the various oils we now use.

One can have fun if magic users can add magic to items. If there is magic creatures one can have even more fun. consider capturing glowing faries and using them for household lights. Magic is used to keep them living.
One might have demons turn the crankshaft of the car, being the engine.
One might have trash cans where things age rapidly so kitchen wastes compost over hours metal cans rust to nothing in a day or so, paper ages and crumbles. It reduces to almost nothing. It does not have to be emptied for months.

One can have computers where the switches on the computer chips are magic not electrical. They might be a whole lot bigger than what we have, or slower, but it might take a simpler technology.

One might have "cans of fireballs" that are combat fire balls made by magicians and stored up. one uses a valve to control the heat for cooking.

The GPS might be magical, detecting several high magic sites and tracking based on maps added to it, rather than by satellites.

There can be a whole lot more done with imagination and the rules of your magic, especially in industry where magic might add to the process like chemical reactions or welding processes.

Most other fantasy novels, for example, will use a technology level less advanced than we are now. That may be why most fantasy stories take place in a medieval type setting. You said you are thinking wild-west type technology, so that fits this as well. And remember, technology is always created by engineers, who create based off of whatever scientific progress has been achieved. Any technology will reflect this (can you imagine an ancient Roman using a laptop? Its anachronistic...) Nevertheless, all stories have some level of technology (whether its a caveman building a fire or a knight getting a sword from a blacksmith, etc) Humans tend to manipulate their environments, and the result, no matter how advanced, is technology.

That being said, remember you are the creator here. You can do whatever you want. At this point, you have managed to come up with a premise only, not a story. Your premise is the world in which the events will take place, one where magic and tech co-exist. The story will come when characters make decisions, interact, and face consequences. Try not to get the two confused Once you come up with a story, you can adapt your magic/technology dichotomy however you need to make it work. Likewise, if you have some interesting way the two can interact, you can use it to help mold your story.

For example, you may have a magic-user fighting a technology user as your central conflict. Inherent in this will be deciding which is stronger. Who has the advantage? Neither? Do you want your main character to overcome huge obstacles? (If so, you'll have to make him a member of the weaker branch.) Do you want him to fall from great heights? (If so, you'll have to make him a member of the stronger branch.) Does he end up finding a way to combine the benefits of both that was previously unknown?

I think when they coexist and there is some kind of market for either, the most efficient will rise to dominance.

For example, if magic can't move large objects, then technology (i.e. a truck) will dominate the environment.

Magicians can make fire, but matches can too. If there is any cost to magicians for lighting a candle (i.e. losing their powers, even in a miniscule way), even they will likely opt for a match.

Teraen, I do appreciate the reminder but don't worry. I realize that this premise is not a story. And as most of you commented I know I have to define my magic to truly figure this out. I was was just looking for thoughts and maybe testing to see if I was possibly barking up the wrong tree. But after all of your comments I think I can make this work.

I looked at my first novel and realized that it needs a drastic amount of world building. In thinking about how I would shape the world I started asking, 'What if?' I also considered that this might not be the best time to be trying to sell high fantasy. While not entirely trying to tailor to the market, I asked myself if I could be happy with these characters in a different setting.

I don't think I feel comfortable with them in modern times or the future. But that led me to consider the Old West. Even when I was writing in my medievalish setting I was tempted to slide into a westerm feel.

One of my current dilemmas is the presence of guns. I am debating between and pre and post-gun creation world. I also thought that maybe the gun gets invented within the time of the story to create a whole new conflict.

My original story had one group (of a different race) invading the human lands. Maybe they have invented guns and the humans have to try and catch up.

I'm always happy to hear more thoughts. Thank you all.

During Nepolian's time, the air powered muskets were already in use. They were more powerful, more accurate and quick to load than gunpowder muskets at the time. Nepolian sent out a decree. Anybody caught with one of those rifles will be tortured to death. They disappeared.

Really, a gun is simply sudden expansion of gas to launch a projectile. One could use magic to do that. Add a magic object into the gun and when it goes off, it sends out the bullet.
the use of such gun might appear to be in a western, but maybe loading the shells is a problem, or it might attact gnats so their guns are always covered by bugs, making it slippery.
The bullet might have a "desire" for hitting something and is being held back by the shell until you pull the trigger to release it. The bullet is not bright, so it goes out straight and when it stops, all the joy of the flight is gone.

Steam in the steam engines can be made by various methods. One could be by mage fire, by demons,or the wood is magically protected so it burns longer or never burns out. There could be a trapped or trained dragon that is blowing fire onto the boiler to build up the steam.

It is a setting where people from each of the four nations can manipulate with the given element - there's magic. But they (Fire nation, at least) are also using technology, so you have armies made of cavalry and tanks. The truly interesting bit were the submarines that used water bending as propulsion. Or baloons using fire bending for propulsion. Or the train that used earth bending for propulsion. Air benders also use their ability to manipulate the air currents around their gliders so they can actually fly.