At that budget you're not going to get a laptop that'll run Crysis or BFBF2 on high settings. My £600 laptop has run every game I've thrown at it on med-low graphics settings. £600 is pretty much $900 - but when you take into account our high tax rates, the fact that we pay more for everything anyway, and that I got my laptop a good 6 months ago - you could probably get a laptop a bit better than mine for that price. But you're still not going to be able to play any graphically intensive recent release on maxed out settings in that price range.
So your choice is essentially this - get a desktop & lose the portability, or settle for lesser graphics. Personally I'm happy to settle for med-low graphics settings on my games - As long as I'm able to fully enjoy the gameplay experience I don't overly care about how pretty it looks. But it's up to you.
If you really plan on playing games properly on this laptop, more than say a fleeting game of peggle, TF2 or something like that, do you really see yourself needing the portability? In almost every case, if the word 'game' comes into the question at all - get a desktop and save yourself some regrets later on.
If you plan on actually using it like a laptop, you're going to have to settle on some reduced settings to get something in that price range.