Thank you Martin, I'll keep you suggestion under advisement, for it is quite a considerable claim that you make, worth of serious consideration.
And thank you Cyril: As great as the iMac is (3.4 GHz i7, 16 GB RAM, one 2 TB HD, 2 GB GRAM), obviously it cannot handle everything (I doubt a single Mac Pro could either), so I was thinking it would house Sibelius, Logic Studio, and the Pro Edition (maybe even some other Kontakt-triggered libraries), and a Mac Mini Server would handle MIR PRO and my SE+Extended VIs, the EW choirs (and maybe those aforementioned Kontakt libraries - whatever's best). I take it both would run VE PRO 5. I appreciate your advice to wait, but of the solutions you proposed, I take it this is the one available to me?
Any additional comments would be most welcome.