I will keep my 4x veloci raptor raid for a while longer tbh.
Ok, mechanical hdd's in raid 0 are nice for unraring files and moving large data files around, but in terms of performance, 4x raptors in raid can't come even remotely close to the access times or small file write performance of the worst ssd's on the market.
Cost wise Raptors offer worse performance than SSD's, they are so marginally ahead of standard 7,200rpm drives, for a huge extra cost, and noise, and lower capacity.
A £100 64gb Crucial is far better value than a raptor tbh.
I have a couple ssd's, and a couple cheap mechanical drives in raid 0 for downloading, unraring and large data duties, best of both worlds, and it would all have costed quite a bit less than 4 raptors, offering better performance all around, with less noise and far higher capacity.
I'd ditch any raptors you might have while other people would still bother paying any money for them.
http://www.anandtech.com/storage/showdoc.aspx?i=3631&p=20
thats why raptors suck, yes its not in raid, but 4 in raid 0 would not be close to 1/4 of the time to load, in which case for a higher cost it would still be slower, sequential speeds scale very well in mechanical hdd's, loading lots of random small files doesn't improve much in raid 0 and is terrible to start with, I'd imagine 4raptors in raid would barely break 20 seconds in that test. The difference is massive.
http://www.anandtech.com/storage/showdoc.aspx?i=3631&p=22
the bottom graph is what happens when you try to load multiple apps at the same time, random reads on hdd's are horrible, absolutely horrible.