It would be unusual (but not impossible) if a repair to a laptop resulted in changes to your browser's display settings. It's more likely that the screen resolution has been changed. (That would also be consistent with your laptop being 'all messed up').
Right-click on the desktop. Select 'Properties' and click on the 'Settings' tab. If the 'Screen Area' slider isn't set to maximum, drag it fully across to the right. Click 'Apply' and then 'OK'
(Those instructions apply to Windows ME but XP should be fairly similar).
Chris