Tomb Raider underworld not working.. why?

go to www.canyourunit.com and see if you can run this game properly, i think the problem is or your processor or your amount of ram, you say you have a 1.86GHz intel, but is it a dual core core2duo, intel centurion?? also your RAM isn't that much for a vista pc, maybe you should give your pc a good clean up, (hard disk clean up, removing program you never use, defragmentation etc.) maybe this will solve the problem. if your processor isn't good enough, you should buy a new one, or overclock it. hope you can play soon, its an awesome game :P