Steve, you will need to know which processor was in the Ti to begin with - as far as I know, they're not completely interchangeable (though some may be within model class). The logic board (motherboard + processor) will set you back anywhere from $249 to $499, depending on which Ti this is.
http://www.ifixit.com/Products/Titanium-DV...gic-Boards/9/33(there are three Ti categories - see menu on left)
They offer very good guides at iFixit -
http://www.ifixit.com/Guide/Mac/PowerBook-...gic-Board/25/9/ is for one model of the Tibooks.
If you're careful and take it slowly, (keep those screws in little bowls, in order!) you should be able to do this. I've done various take-aparts on Powerbooks, iMacs etc. It's usually not particularly difficult if you follow the directions!!
Of course, you have to decide whether this worth the $$$ and the effort. Logic boards turn up on eBay too - often for a lot less. Of course, you don't have the same guarantees there. Also - if you look on eBay, you may be able to get a replacement Ti for the same price or less than you'd pay for a replacement logic board at iFixit. Just depends which model you're looking for!
