Well, obviously the best thing to do is to go out and test drive the cars in question. I just came home from looking at several dealerships and didn't run across a single 350Z or STi. PLENTY of trucks and SUVs, though. Maybe I'll have to wait until winter is over to do any test drives... Since quite a few people suggested it, I'm going to look into the Legacy GT as well. I'd really like to have leather and a sunroof, and AFAIK the STi offers neither.
Another option that has been suggested to me is the S2000, but talk about impractical! I once owned a supercharged Miata, and talk about not being able to carry a bag of golf clubs around... :Q
As for the concerns about my job, don't worry: in all honesty I could afford to buy a car before I got this job. It's just that this will make it easier to handle when those unexpected expenses arise. I will be bringing home roughly twice what I did at my old job, so there will be plenty of extra money to throw toward investments/entertainment/etc. I know the "smart" thing to do would be to buy an old beater and invest or save every last penny, but hey you only live once, right? Besides, my girlfriend is a nurse and we plan to get married within the next 12-14 months...at which time a car payment won't be a big concern at all.
I do appreciate the comments and input, though. If anyone has any additional suggestions, keep them coming and keep it civil!