Installing a new Motherboard under WinXP

Recently upgraded a computer running XP Home with a new Motherboard, CPU and Ram (Gigabyte GA-8SIMLH MB, 256MB PC2100 DDR Ram, Intel Celeron 1.8) for a client. Removed all drivers for HDD and MB etc before installing new MB, get blue screen of deatheverytime I boot with the new board (Remove any recently installed Controllers, check for viruses, run CHKDSK/F and reboot). Tested with a clean HDD and installed XP OK! Have tried everything to upgrade without re-installing XP! Any hints or ideas on what could be causing the problem are welcome, I have done this before without any problems! Now I just want to find the answer to this one!

Thanks.