I upgraded my PC recently to the following:

DFI nf4 skt 939
A64 3000 @ 2.7GHz
2Gb Corsair Value RAM
Gigabyte 7800GTX
2 x WD 10krpm Raptors (RAID 0)

Tonight I've noticed some issues in Photoshop, both CS and CS2. I can't remember if these issues have been like this since just tonight or since I built the system, I know however I didn't suffer them on the previous system.

Basically, when I drag a layer it's not refreshing. In other words, I drag and the layer doesn't move, it isn't until I release the left mouse button that the layer moves to it's new position. Obviously this is a little annoying for precision work. If I hold down LMB and move my layer, then wait to see if Photoshop is just taking an age to redraw the layer, the CPU usage shoots up to 100% and remains there until I release LMB.

Any ideas how to resolve this issue?