SC - it wasn't me who suggested a Mac. Nor would I recommend Betamax VCRs....
System restore is an utterly simple process. Just go to 'Start', then 'All Programs', then 'Accessories', then ' System Tools', then 'System Restore' and follow the easy guide. It'll basically reset your computer to the way it was on any date it knows about!
I don't know why people whinge about SP2; sure there've been a few isolated interactions with other programs, but it works 100% fine for me! But if you want to uninstall it, it's easy enough under 'Control Panel', then 'Add or Remove Programs', then scroll down to Windows XP Service Pack 2 and remove it. If you must!