I have to ask the same as the OP question - if this machine is purely a gaming device, why pay a penny more for unused features? Even if it's 'only' £10?
I just spec'd my new gaming rig, and went with 64-bit basic. I'd have gone XP [hell, I'd use DOS if it meant I could load games easily], but the native 64-bit and facility for future games sold Vista to me. I will not be using this machine for anything other than loading games - I have a mac for everything else, and so I already have one eye-candy OS. Although Aero looks as lovely as OSX [no mac-fanboyism here, I promise - I sit in both camps], if I don't need it, must I pay extra?
This is a genuine question - I asked in another thread if there was any reason I'm selling myself short. For an extra £10, if there's a gaming feature I'll need, then I'll swap my order straight away.