GOD I love this site.

These are EXACTLY the kinds of posts I love reading!
I am a little worried about the PSU... it was purchased at just 300W a few years back to save some cash, and because it would do fairly well supporting my current system. Come to think of it, however, I'm not sure if it supports the newer video cards that require their own power lead; my case side isn't screwed on (just put in place), so I'll look in a bit.
I do, in fact, already have the CPU; it's basically a spare system I've got laying around, but it's not really any better than my current one, and is a Compaq-built, rather than my self-built. But hey, the price (that is, free) was definitely right.

I'm 90% positive the CPU will work with my Mobo, and it will be an upgrade, but nothing much noticeable. Still, it's an Athlon XP instead of a Sempron, and I'm pretty sure it's got more cache, so it's something. No sense in not using it. Nothing to write home about speed-wise, but still.
It's good to know I should go with the GF 7xxx series (assuming I go NVidia)... I probably would be going with a low-end 7600GS model. I'm also looking at a hard drive upgrade (another reason my budget is so small), so I may be splurging today...