MSI K7N2 Delta L Problems, won't install windows...

I've recently had a problem with memory errors caused by my old Leadtek nforce2 motherboard, constant freezing, crashes, etc.

I have just installed a new MSI K7N2 Delta L motherboard, ran windows memory diagnostic - no errors! Great, or so i thought.....

I reinstalled windows, it froze first time so i did a repair, installed it... but there were still instability problems as i tried installing hardware once more...I tried reformat/reinstall once more...now it won't even install windows on my system. HAve tried with 2x 256MB Nanya DIMMS and 1x 512 Crucial, then 2 x 256MB Nanya in dual mode, then 512MB Crucial DIMM on its own. All DIMMS are 333 PC2700. Still no joy!

Memory diagnostics, fine, Hard Disk diagnostics (official Western Digital one), fine.

The only change is the mobo, now i have a heap of mostly fully functional components that i'm seriously considering dropping in the bin because something's not working and i can't work out what!

Athlon XP 2700+, 256MB Galaxy 6800GT, WDC 120GB HD, one floppy, one DVD drive connected. Tagan 480W PSU, Thermaltake SilentBoost HSF on CPU, Nexus 80mm case fan.....have removed Audigy 2 and TV tuner cards...

HELP!!!