I own an Early 2008 2.4 Penryn MBP and the only problem i have had is the fans failed at around the 3-1/2 year point, however it did spend over two years in the Middle East sucking up dust and it has over 35K hours runtime. This being said i would not recommend, as too many have had issue with GPU failure, and as others have stated repair does not guarantee any long term fix.
My own Early 2008 has served me more than well enough and is now basically retired, i would keep the 07 machine a little longer, save some and buy a MBP that is not afflicted with the Nvidia GPU issue. There is now no longer any support from Apple, if the Logic Board fails you will be on your own, with a large bill...
If anyone has a MBP with the Nvidia issue, the only thing you can do to extend the lifecycle is monitor the temp and keep the GPU as cool as reasonably possible, for this i recommend
UltraFan and elevating the MBP