Re: Velociraptors -- I still have 2 of them; a 150gb and a 300gb. I used the 150gb in my Mac Pro for years as the boot drive, before SSDs really started to become affordable. The performance boost vs. 7200rpm drives is VERY noticeable. I never had a problem with noise with either of mine. 

I acquired a 2007 24" iMac from work - it had a blown PSU and they were just going to recycle it. I bought a new PSU and replaced the stock 320gb drive with the bigger Velociraptor and it really scoots. A 300gb (or thereabouts) SSD is still a little pricey for my liking, so I'll stick with the Raptor for now. 

I need to find a use for the 150gb - maybe if I come across another iMac sometime...