http://www.microcenter.com/product/403254/ProBook_4540s_156_Laptop_Computer_-_Brushed_Aluminum
This one is damn cheap for the specs it has. 2.5 GHz i5, 7200 rpm HD, 8 gigs ram. You're probably not going to find a better pre-built comp for money. If you want to build your own, you could save additional money by installing ubuntu instead of buying windows.