Though the truth is I pretty much replaced it.
The only stuff I kept from my old one was a 250gig SATA HDD, my 2 gig a 3200 RAM, my chassis, PSU and all the other essentials like monitor, mouse, keyboard etc
On top of the above I now own:
Powercolor HD3870
AMD 64 X2 4800+
400gig SATA HDD
nForce4-4X motherboard
Yay me, not a huge upgrade but itll do me just fine.