I think the first gen Altima could do well. We'll see. As was said before, power is not everything. In fact, too much power and too many mods could hurt you, depending on what class and venue you decide to compete in. The best example I can think of is this: Have any of you ever heard of the Honda Challenge? It's NASA roadracing, any Honda can compete. They are on the web at
http://www.honda-challenge.com For Nissans, the SER-Cup exists. However, let's say you have a 91 CRX Si with a 1.6 liter D series motor. It's a peppy little motor, and a CRX with this motor can be very effective in the class it is supposed to be in. However, let's say you abide by all the rules, but you swap in an ITR motor. You'll still have a fast car, but unless you are a damn good driver, you'll be getting spanked by NSX's and modded S2k's. This is because you have to change classes.
If you are serious about getting into motorsports, the best thing to do is first decide the kind of racing you want to do and have the budget for. Then, get a copy of the rulebook and mod your car depending on what class you would like to compete in. By all means, make sure your car is first in mechanically excellent shape. You have to pass tech before you get on the track. It would suck to spend a fortune on suspension mods and have the tech fail you for something stupid like leaking CV boots.
I would say the best thing to do, in order to get a good feel for your car is to drive your car basically stock for a season. This will A) show you what areas of the car need improvement, and b) help you to improve your driving abilities before going to the next level.
Remember, the most improtant thing is to have fun. Also, remember that this will be expensive and time consuming, even if you are driving your car basically stock. Don't be alarmed about going through a set of pads and rotors in a weekend, if you get my drift.
Hope this helps. I'm by no means an expert, though. Check out the SCCA and the NASA forum for more info.
http://www.scca.com