First - you don't upgrade XP to Win7...You REPLACE XP with Win 7. To use an UPgrade version of Win 7 you must have a licensed/activated version...
OK...now I see the part about hard drive from one pc to another. (i'd never do that but it does happen) You basically have to do a Repair...
In Device Manager - you can uninstall a device.....shut pc down to add new hardware....turn pc back on.
Question #1 Control Panel->System Icon->Hardware tab->Device Manager Click on the Computer Name then click on ACTION->Scan for Hardware Changes
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