To be on the safe side. Have at least a gig of ram (At least this works great for OSX/ Mac users. I don't know about PC). A dedicated audio drive with around 35-40 gigs of space on it for D.F.H.S. Why don't you just go to ToonTrack.com and all of your questions can be answered there
And remember A) You don't NEED mic bleeding 'ON' when programming, it'll automatically convert during the bounce in the D.F.H.S. sampler. And B) TURN OFF Cache! Many many many many users forget these two easy directions and immediately start to b*tch about why their computer will not run D.F.H.S.