Yea, the access times may not sound like a big deal, but it really makes a noticable difference. For instance, I recently built 2 identical computers, but one was equipped with a raptor for the OS and one just had a seagate perp. recording 9200.1 or whatever the designation is. The raptor booted into windows in ~9 seconds, whereas the seagate took ~19 seconds. I personally use one to keep my OS and some select games on, then run a couple 250's for storage and general use.
i know the capacity difference is in favor of the 400GB drive, which would typically indicate higher STR (at least when comparing drives with the same rpm)... but referring to THG hdd charts, it seems that both faster access times, and STR are in favor of the 74GB raptor
Raptor is faster but you have no capacity. So what you do is get a Raptor and give a 20GB partition for Windows and a second partition for your installed parograms. Then get a second high capacity 400GB or so drive for all your storage needs.
Otherwise you will want several regular 7200RPM drives set up as a RAID to get similar performance. Set up Raptor drives as a RAID and you'll be smoking.
I'd say Raptor is reserved for the exclusive high end gaming systems or people who want to show them off at the LAN. Other than that multiple 300GB Seagates are my choice. Several of those is cheaper than a 700GB drive. Just RAID them up for performance and fault tolerance.