Well, from the looks of it, you should be able to run it, but I'm sad to say that it'll probably only run at the lowest graphics settings, especially at that resolution. That's okay though, the game still looks pretty even at the lowest settings possible.
Also, getting a new graphics card isn't going to do you much good. Your CPU will prevent it from running at its best. My suggestion would be to get an entirely new computer. PC Gamer has a running parts list for low-,mid-, and high-end machines that is updated each month. The low-end usually runs about $500, and is quite fast for the price. Hey, if you work hard enough, you'll reach that $500 in no time.
Minimum System Requirements:
Windows XP, Windows 2000, Windows XP 64-bit
512MB System RAM
2 Ghz Intel Pentium 4 or equivalent processor
128MB Direct3D compatible video card