@Timotheus I would upgrade 3x1GB Corsair DDR2 to a 2x2GB or 1x4GB DDR3 if you got the money it will run abit faster.
If you get new fans I don't know if you have case cooler but I would recommend a overclock and windows 7 64 bit to get the maximum preformance.
Like locolagarto mentioned windows 7 works best, you have a nice rig overall.
I'm gonna create a new case, I'm gonna sandpaper the case and spray it black and make custom logo on it.
Furthermore I need abit of case design I'm trying to get a "kuroFECAL MATTER!suji" (anime) style case, I know an airbrusher but I need to have awesome design.
I will post the case that I'm gonna mod later it has neon lights in it : D
I noticed that sh*t is cencored the name of the anime is kurosh*tsuji and kuro means black sh*t suji butler so it wasn't wasn't meant as an insult D: