@Dan Scott, indeed, I have many reasons for doing that, and being sure that drivers are available is among my reasons.
Amusingly, I just got a "real upgrade" today: I had a 2GB RAM for a T61 sitting around unused, and so now I have 3GB RAM instead of 2. Mairix indexing doesn't cause my machine to thrash anymore. :)
(Side note on my side note: thrashing is in the tradition of Computer Science to use terms that sound really bad to refer to things that are somewhat bad. I'm thinking of things like abort, fail, crash, etc.)