It's mostly a matter of how fast you want to nail. I have used many sizes on my nailer, from .5HP/pancake to 30 gall/5HP.

Pancake able to fire 3-4 nails with a minute or less inbetween.

I do find my 2HP/5gal to work best, portable and able to keep up to my nailer set at 90psi with 2-1/2" clipped nails.

Consider future use rather than just the room framing project. Most pancakes or portables will handle any nailer. You might want to get a larger cfm'd unit in order to run future tools such as grinders, impact wrenches, cup sprayers, etc., that require higher cfm's. If not, a pancake or portable will handle nailers as well as filling auto tires. If you are out to purchase a nailer as well, it will state the required cfm's. Here's a few from amazon. Most have free shipping.

Here is a link that might be useful: air compressor

You need a 5 or 6 gallon portable compressor---several companies make them---Campbell Hausfield, Stanley Bostich, DeWalt, or my favorite, Porter Cable.

With all the above brands, you can buy the kit---nailer/compressor/hose/fittings.

Agree with Sierraeast and Handymac -- nailers don't consume much air, so almost any compressor is likely to work for your purposes. A friend has put on several entire roofs with a tiny one-gallon, 1.5HP compressor that cost than $100, and he's very fast with his coil nailer. Spray painting, pneumatic sanders and grinders, impact wrenches and the like are the sorts of tools that make CFMs a significant concern. For wall framing, you have little to worry about.

Great info guys. What do you think about the one in the link? Also, are all accesories for all brands normally compatible with each other? As in can I use a Husky Blow Gun with a Porter-Cable hose?

Here is a link that might be useful: Porter-Cable 3 Nailer Compressor

That compressor should be fine, but note that none of the three nailers in that package is a framer; they all shoot small fasteners for trim and other light-duty work.

Most air tools and hoses use compatible fittings. There are exceptions, but you're unlikely to run into them. Fittings are widely available, and the male connector on most tools can be easily changed to match your hose(s).

The one listed below is a pretty good deal.

Here is a link that might be useful: PC framer/compressor combo

I forgot to say the clipped head nailer is usually building code compatable for non load bearing interior wall construction.

Clipped head nails are not code compatable for most exterior roof and load bearing wall construction.

Clipped head nailers/nails are less expensive than full head models.

I used this buying guide to help me decide which I needed, maybe it will help you. Let me know if it does, thanks.
-Jonathan

Here is a link that might be useful: Air Compressor Buyers Guide