If you're doing photo or video editing, and want it to happen at any speed, you want a good processor. i3 or i5, if you're going to be doing a lot of it, i7.
You shouldn't get a machine with less than 6gb of ram.
I'd also highly recommend looking at a SSD, however, that will also increase costs.
http://configure.us.dell.com/dellsto...en&s=bsd&cs=04
though, I'd opt for Win8 at this point, but I am a big fan of their Kool-Aid.
I don't think you're going to get away with what you want until you bump your budget a bit.