Given you’re ok with raid (IE: You have a back up strategy) you have the following type of options to consider, which includes the following myth buster:
1 Fastest:
Standard Drive for your boot disk. (you could raid this but it will only make the computer boot faster).
RAID x 2 Drives (or more) for your images / files / input + output.
Backup up drive – auto configured to run a system back up – if it’s important to you.
Move all program libraries (itunes, bridge, email etc… to the raid or back up drive).
Keep anything you’re actually working with inside the machine hooked up to it’s own SATA drive and use software RAID.
2. The Illusion of speed:
RAID (x2 drives) your OS
Raid (X2 Drives) your files
Same as above – but now it will boot in about 7 seconds or less depending on how much RAM you have.
3. Buy more RAM (Faster RAM).
The above assumes stripped performance RAID’s. Now the myth buster – you can have your scratch disk portioned on your OS drive, there’s no need to dedicate a drive to this – it will not run any faster fro oding so.
Finally set up Photoshop and what ever other CS5.5 apps you’re running correctly – scratch disks, image cacheing, history states etc.. all have a big performance impact – as does the navigator (ditch that).