McIce,
I think your best bet might be to do a system restore to a point before your brother ******ed your computer up.
It's very easy to do with XP, and if it doesn't solve the problem, you can undo the restore.
Just go to START then...
START-ALL PROGRAMS-ACCESSORIES-SYSTEM TOOLS-SYSTEM RESTORE.
Pick a the nearest restore point before your brother changed the settings.
Hopefully this will revert the computer back to your desired settings
419