I am a windows user wanting to make the switch to Mac, I am thinking of getting a 20 inch Imac and wondering how well it runs windows and if it would play games like counterstrike and battlefield 2 thanks
Hi BrentonX
Using BootCamp (which allows you to partition your Mac's hard disk to make room for Windows, and provides you with a set of Windows drivers for your Mac hardware) is the way to go for gaming.
Essentially, you can dual-boot into Windows. Power on the machine, hold the Option key and it'll allow you to choose your Windows XP installation to start up with.
When running XP, the Mac is basically an absolutely standard PC (albeit a very quick one!) Windows will run *exactly* as it would on a regular PC, with the same performance. I dual-boot into XP on my 2GHz MacBook Pro for gaming. It's great to be able to reserve my Windows setup entirely for gaming - tweaked exactly as it needs to be for games and nothing else. I play Battlefield 2142, BF2, Half Life 2, Dawn of War and lots of other games. I can almost always run at high detail levels, although I drop it down a bit for the Battlefield games since the explosions can drag things down a little.
I use an external Firewire hard disk to install all my games to -- so I have a 10GB partition on the internal hard disk for Windows itself, then the 120GB external drive for all the games. Loading times are a tiny bit slower due to the external drive (it's only Firewire-400, not FW-800), but aside from that, performance is great. It'll be 100% compatible with all your Windows-targetted hardware - I use a XBox 360 Controller for Windows as a gamepad, and a Saitek Evo joystick for Flight Simulator X (and flying the aircraft in Battlefield!) Everything works great.