System should comfortably run 2 x WoWs and fraps as you wish.

Worthy upgrades would be a quad core CPU in case you ever want to quad box (trust me you will :P)

As another poster mentioned, Vista 32 is probably slightly better for 4GB ram than Vista 64. Saying that an extra 4GB is easy to drop in for V64 if you ever do want to quad.

I would consider a 650W PSU possibly esp. if you want to consider a quad core CPU with that GPU.

Cheers