So, the Mem 4.20 checks were a complete pass.
the XP Pro works also fine, there has been no change since upgrade of CPU from 4400+ to x4 640.
i got ddr2-667 cas 5-5-5-15 333MHZ RAM, not very fast one, does a faster one make much of a difference?
I upgrade xpu because the speeds were getting a bit slow and I had some spare money to upgrade. It seems it was the wrong part to upgrade as performance just doesn't respond much.