T9300 CPU
You'll have no problem finding a good Penryn CPU. The T9300 is probably best for your money... and you'll be better off in terms of cooling.
14.1" FX570m SYS Board 42W7650 or 42W7874......A Long shot but I thought I'd put it here
Heh... long shot is an understatement. I've played with my share of T61s and I can tell you: the FX 570M runs HOT. As TuuS said, most of the FX 570M boards you'll see just have a sketchy history, either being sold at the slightest hint of pre-failure, have other (for now) working chips, or have cheaply soldered or reballed FX 570 chips on them, good(post 08/08) or not.
The NVS 140M runs cooler, but I've had the pleasure of gaming on an FX 570M, and I can tell you for a fact, it's probably nicer than the W500's FireGL V5700 if you really push it. The NVS 140M is a sharp compromise, but people go for it because it's still dedicated and therefore far superior to the GMA X3100. Plus, because of the far less violent thermal cycling, pre-08/08 NVS 140M boards(especially the good ones) have a whole lot more life in them. But in buying online, anything still goes, just like with the FX 570M.
As for the board, even if you're planning to just use the 14" T61 chassis... I recommend that if you want NVIDIA graphics, and you want a board now, you should get one of TuuS' NOS boards. It may be a bit pricier than cannibalizing a still working T61, or getting an odd Merom FX 570M board that happens to work, but it's a decision you wont regret. There really is nothing more fantastic than the security that your 4:3 T61 motherboard is exempt from the NVIDIA terror.
Indeed good luck with your project!
Trying my hardest to collect Thinkpads, but college and being broke kinda gets in the way. However...
701C, 760, 770, X24, T30, G41, A31p, T43p, T60/61 Frankie, Z61p, X60 SXGA+, W700ds
MEDESSEC
and yes. I am a bit of a lunatic.