I am impressed how do you change machine every 3 years!, is 2500USD each MBP, I have my 2 years old 1rst revision MBP and It will last me 2-3 more years. A lot of users change from CD MBP to C2D MBP, the difference is not big jump (not even 2x), minimum 2x performance to change machine. My machine is plenty fast, even with Leopard, It still use my dual 1ghz G4 with leopard to do seirious photoshop and final cut work (6 years old machine).
A lot here are just apple adicted.... (me too) but you have to use the computer until the last breath. Maybe upgrade HD, ram, but change the computer for the super multitap blaaa.. for the 512 MB crappy card...I you want to play get a PS3 WAYyyyyy cheaper, wayyyy better performance....
Just my 2 cents.