USB Mouse and Keyboard Problem

Hello,I've just installed an Asus M3N-HT DELUXE Motherboard on a dual boot,XP Pro(32bit) and Windows 7(64bit).They are installed on seperate Hard-Drives,and the Motherboard is the only thing I've changed(old mobo overheating)Everything works fine in Windows 7,but when I boot into XP both mouse and keyboard freeze.There is no PS/2 for the mouse on this board,just for the keyboard.Both mouse and keyboard are USB anyway.Have tried different USB ports but still the same.XP picks up new hardware found.but with no mouse or keyboard I'm stuck.Could I do a Repair on XP or will I need to install XP again because of the motherboard change.Both XP Pro and Windows 7 are full retail versions,and XP has SP3 installed.ThankYou in advance for any help. Grandad63 in BUCKIE Scotland