PC, maybe, but for the 360 I manage just fine with the controller.
Come to think of it, why not purchasing the Xbox 360 controller for Windows? I use it for Halo PC - it beats a mouse and keyboard any single day of the week.
for an experienced xbox controller player that would be a piece of cake...but as i'm used only to pcs...well it'll get some time to get used to
but i'd rather buy a whole xbox 360 cos at least i can always play a brand new 2007-2008 game with all graphics at high or very high at high frame rate instead of always upgrading my pc for each game
and i think it's even cheaper to get an xbox 360 which you said it has tons of games which some aren't even available to pcs than to upgrade your pc for each game that it's released