Ok, i got a 650W PSU and attached that to just the Motherboard, HDD and DVD ROM, and it still restarts at the same point.
I ran Memtest-86 on just the new RAM and it came back without any errors
There are no beeps other than the one between the graphics card bios screen and the normal bios startup screen, and that one has always been there.
Oh, and i dont understand what Posting is :P
EDIT: I just tried running a windows 2000 cd and it booted to the install screen, so i got a backup copy of XP and ran that, its just got to the setup screen....
I dont understand why that is working, but i'm going to reinstall XP and hope...
I'll let you know if it works.