I'm using a Velociraptor as a dedicated HDD for my OS, i.e. Vista 64-bit until W7 pro comes out (W7 RC1 is on another HDD). Boot time(s) speaking, the raptor does give me a fast boot, especially of Vista, but nothing ground breaking. W7 should boot even quicker. Depending on your budget, you may be best served to go with an Intel SSD- check out Tom's charts for more info. They can be pricey though, so if you don't wanna blow that kind of cash and want to wait for prices to go down, go with a raptor or a spinpoint for an OS drive.