Readyboost for Vista is a feature added to the OS where you can encourage your limping Vista install to jog a bit faster by essentially using a smallish USB drive as disk cache.  There’s also some Vista Voodoo with Superfetch going on there. While Ubuntu (the distro that I use) and other distros don’t really use Superfetch, you can still get an advantage using the disk cache functionality - particularly if you’re running on a system that doesn’t have a ton of RAM available.