how can i increase my resolutions?

put your thinking caps on... i upgraded to windows 7 beta and i found that i needed 1600x1200 so i went to adjust my resolutions but i found that my resolutions is 1680x1050 so i am at a loss to figure out if i need a new monitor or graphics card and beginning to think it is in my motherboard and processor was going to ask microsoft but they will call in a few days so here is an enteresting one for you tech minded people out there in cyber land. please don't tell me to get lot's of rest and drink a lot of fluids a doctor can't help with this problem but i am about to spend some money and want to spend it wisely. so help!