harddisk setup??

hi there all

i'm trying to budget a medium quality editsuite.
based around FCPstudio2 a MacPro8core EpisodePro and a Blackmagic Decklinkstudio capturecard.
I'm getting confused with the harddiskpart what is the best choice??
my work will be SD and some HD most work is CutCut some titling simple DVDauthoring.
transcoding.it will be more a kind of utility suite then a full creative paradise ;-)
actualy the machine will mostly be used for transcoding or encoding tape's(old archive stuff) to file's.
my question what will be the best harddisk setup. is it true when i say that using prores to capture will
unstress my harddisk setup but will stress my processor. or the other way around will my disk setup be more complez/expensive when i use uncompressed but will this ease transcoding.

greet
Maurice