You dont need to upgrade a PC every few months - get a decent graphics card to start with and you'll be happy for years, especially if you get plenty of RAM to start with too...
Slim-case machines are good for office work where the machine wont be opened (or taxed in any meaningful way) and some bored person will just be pressing the send/receive every few seconds...
I, personally wouldn't go back to console gaming - trying to use a joystick for a FPS is like trying to extract a tooth with a feather, with the duck still attached.
Plus there are other advantages - cheaper gaming for a start. The only real advantage a console has is that you can rent games.
Another disadvantage of the console (with the exception of the XBox range) is that you aren't legally allowed to program them...
Edited by deleted (Thu 19-Jan-12 00:42:13)