Looking at a system for recording it is important to look for where the bottleneck of data may be.

Often it is not enough RAM to allow the processor to work optimally. That's why my first suggestion was RAM. It's the biggest bang for the buck usually. Biggest improvement in performance (in many programs, just just recording) for least amount of cost.

Next is drives. If you start out recording only a few tracks you'll be fine with one drive. But imagine your hard drive trying to read 16 tracks of audio while at the same time trying to *write* new audio that is being recorded. This can lead to a drive thrashing around to keep up. Sometimes this will show as problems with smooth play/record functions .. but sometimes it shows up later as wear on the drive from jumping around so often.
Data (recordings) are important here so I try to have one drive for playback and another for recording too (and others for acking up).
This alleviates some stress on the drives. Not always necessary, just something to think about, which is why I asked.

My newest system has a triplecore processor (saves a LOT of energy over comparable quad core), 6 hard drives and 4 gig RAM ... and works great for the intended purpose. Two of the drives hold backed up projects (paid) and personal projects from the past.. so that data is pretty safe. The other 4 drives hold: 1.OS & programs, 2.temp recording folder (for writing new incoming audio tracks), 3.current project saves, and 4.main OS drive backups for multiple systems.
Never too much storage!
I just ordered a USB DVD burner so I don't have to put another drive inside. I have the room and connections but worry it may mess with the SATA buss the other drives are playing very nicely on currently.
OK, maybe I overthink this stuff. But it sure runs reliably.

I do not work here, but the benefits are still awesome
Make your sound your own!