I have a C2D T9500 2.6/6M in my workstation laptop HP8710W + 4 gigs of ram and Windows 7 Ultimate X64.
C2D mobile processors T9400+ are great and fast enough for gaming/rendering. For multitasking quads like i7 are better, but if you do lots of hard tasks at the same time better get a desktop
The best upgrade you can do to your laptop is SSD drive.
I put in my laptop 120GB OCZ SUMMIT 220/200 and this is it, laptop is super fast, photoshop launches in a few seconds, almost like notepad.
So if you need it for gaming get a fast C2D processor like T9900 + high end gpu, if you need it for multitasking get i7 + middle range gpu
