Help me build a PC...or two

Hey guys, if everything goes as planned I'll probably be accumulating the parts to build at least one computer in the next couple months, maybe two computers (although probably not). My girlfriend and I are going to be getting a place and we'd like to play video games together. Here's what I'll task you to do if you want:

Build me two computers, a low-end one with a maximum budget of $800 or so (no monitor) and another one with a maximum budget of $1300 (no monitor of course). Don't worry about speakers either. We really do not play any intensive games yet, but I really want something that will be okay for a few years.

In case you're wondering, I'm not asking for a low-end for her and a better one for me . Just trying to see what you guys think would be the best bang for the buck while also lasting for a few years and being able to play games that come out for the next 2-3 years.

Thanks.