20-25 range. I started out on Nintendo, Super Nintendo, and Windows 95 games. Counter-Strike and Soldier of Fortune were may top games I used to play back then (both PC FPS). Then I got an Xbox and stopped playing PC FPS for ages (I never got very good anyway because I only played them at a certain friends' house). Then I got a 360, PS3, Wii, etc. Wasn't until last year that I got back into PC FPS and found out how easy it was.
Still prefer controller, though... and wish there was a good mouse + controller combo.