Somebody like Mark will probably recommend building your own computer, but personally, I would recommend either an XPS 8300 (which is what I have) or an Alienware system. Considering that you're willing to spend up to $2500, I'd recommend the Alienware, which costs $2199 for the cheapest desktop model. Now, if you want to go with an XPS 8300, look at my specs and possibly get the next processor up and go with the AMD Radeon HD 6870 instead of the 6770 (though you need to make sure your power supply is good enough). Adding a second video card would work well, too.