Just remember many of these laptops have plenty of CPU for the non-graphically intense things they see and that many times an SSD is more bang for buck.
I had a T60 Thinkpad that I took from 1.8GHz? to a T7200 as well, Scorpio 500GB and swapped the GMA950 motherboard to one with the X1400 graphics card. I wanted the V5250 (it went from 128mb to 512mb of VRAM), but many said those cards overheat and use way too much battery power. I also upgraded to Wireless N and the SVGA+ screen. Other than that the laptop had everything else from the factory except the cellular card.
While it was a little laggy with the original CPU, the T7200 ran everything in the MS Office package and browsers not much differently than my near 4GHz AMD 955 in my desktop. I transferred my MS Office license to my Fiancee and put Open Office on his laptop and that runs a little snappier it seems.
About a year ago I gave it to my fiancee's 10 year old as a 'starter' laptop. These T60's are rugged. He has been good, dropped it once because he fell asleep with it and broke the bezel ($5 part) and the Scorpio died. I can't remember what I put into it.
Based on what I read and the costs, unless you can score a TL-66 cheap (I scored my T7200 for a steal by searching VARs I had access too, the two faster T7400 and T7600 were going for brain damage money like almost all the top chips in a socket lineup do...I ended up with 2.0Ghz when 2.16GHz would have been 4 times the price and 2.33GHz over 8...I paid around $25-50 IIRC, the only T7600's I found were $300 or more)
Good luck, I love breathing life into old hardware. I help a lot of my friends/family do this without having to throw another $500+ on something that's just going to run email and Word the same way (and facebook games

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