Your best bet is Dell XPS again... as they allow some customisation of purchase. Upgrading Dell computers is a pain though. And I'd advise against a 17" screen as notebook GPUs are optimised for 15" screens. You can get a fairly decent Dell XPS for about US$1,200-US$1,400 that will run most modern games admirably, but the graphics cards are all mid-range at best so won't have the longest service life. I believe they have 15.2" screens.