Drives with 8MB cache are typically faster.
However, if you have 2 different drives in RAID 0, you're going to be limited by the slowest drive. So unless you have 2 120GB WD Special Editions with 8MB, might as well buy the regular 2MB Caviar.
Click on the database button.
Check the drives you want to compare.
Should be all the info you need.
P4 2.6C, Thermalright SP94/Panaflo 92MM M1A, IC7 Max3, Swifty MCX159, 1GB Geil PC4000 Ultra Plat, Radeon 8500, Audigy 2, 2X WD Raptor RAID 0, WD 250GB SE, Plex 708A, 166SDVD, LianLi PC75, XP Pro.