I think the main advantage of the raptors is supposed to be the seek times... I cant remember exactly but I think the 74gb ones are supposed to be 4.5ms? And normal SATA drives are 9ms... Also one 74gb raptor is supposed to be similar in performance to 2x 36gb raptors in RAID 0, however going to 2x 74gb raptors in RAID 0 doesnt give a lot of a performance increase.
I still the think the best drives on the market are the Maxtor Maxline IIIs, 300GB 16MB cache Native Command Queing and SATAII (if your SATA controller supports NCQ and SATAII) with performance around that of a 74GB Raptor all for less than $1 a GB is pretty good...