That's easy. You can't move an OS from one PC to another. Just reinstall on your wifes PC and things should be fine.
I formated & install Win XP home on my old Sata WD 80gb HD.
It boots fine on my XP PC (Asus P5K3/P5K premium) but, on my wifes XP PC (Mobo Asus F1A55M LE) although is visible in the Bios Setup will not boot, it goes up to the lines left to right & reboots for ever.
It even shows & is read by win. explorer (of wife's PC) when is pigybaged on onother HD that boots.
Even tried he "R" on the WinXP CD in desperation with no luck.
Any help will be apreciated ..........thanx .........nick