What do I need to know to buy an SSD drive for a 2008 MacBook 5,1? I'd like to buy an SSD drive for my MacBook aluminium (MacBook5,1 from 2008). What do I need to know to buy one which will work fine with it?

I.e. years ago any IDE drive would fit any IDE slot, but I've never worked with SATA drives so I don't know if they are "just compatible" or there are some quirks, similar to what happens with RAM where you have to check the clock rate.
A partial answer:  Other World Computing has extensive tables for their own use of what is compatible with what.  They are also good at answering questions by email.