SATA, because youll be using youre OS constantly, which means your OS will work a lot better. That's just one mans opinion. Plus I believe the Raptor has a lot better features like NQC, I think it is which basically helps your HDD to be more efficient.
Personally I would use it for my OS and other apps I use on a daily basis. FASTER is BETTER. I would probably use the IDE for secondary storage and backup.
AMD Athlon 64 X2 4400+ / DFI Lanparty UT NF4 SLI-DR Expert NVIDIA Socket 939 / FX GeForce 7800 GT 256MB GDDR3 / 2x1GB of G.Skill PC4000 DDR500 18.104.22.168 F1-4000USU2 / 19" Kingston LCD / 550 W ULTRA X-2 PSU / JBL 5.1 / PS CS2.0 / 120 G 7200RPM I also have an Olympus Evolt E-500 digital camera and 9" WS portable DVD player.