I'd like to upgrade my old MacBookPro2,2 with something like a 120 GB Samsung 840 Basic SSD. Does that make sense?
I have a MacBookPro3,1 myself and have thought about doing this as well. You will see a little bit of performance increase in boot time and overall usage by upgrading it. In fact, ifixit.com may even sell kits for your computer's hard drive replacement. It really boils down to do you want to shell out the cash, knowing that Apple will, if it hasn't already, cease to support your hardware. Meaning that at some point, if it hasn't already, newer versions of OS X will not be able to be installed on your machine.
I'm still on the fence about upgrading to a SSD on my MBP because I know that sometime in the next year or two I will probably get a new machine to replace it, along with my iMac. If you have the cash, a better investment may be to sell your laptop and use those funds to buy a new one. Just my two cents.
here is a link to the parts that are sold by ifixit.com for your mac, but please verify that I have linked to the correct model (A1211): http://www.ifixit.com/Store/Mac/MacBook-Pro-15%22-Model-A1211