I'm wondering if anybody out there has experience with setting up a music lab on a CC4 System?

We've already got 16 machines on CC4 which are connected to all the usual music periperals and using Cubase SE & Sibielus etc. The machines are old, P4 3ghz and 1GB of RAM (so pushing it on CC4 already ) and they're very inconsitant with sound problems. Audio dropping out, music keyboards dropping out of the program reboots seemingly the only way round the problem. Causing quite a bit of disruption - Done most things to try sort it but it seems that Cubase isn't a fan of CC4 services running or permissions on the PC.

So looking at whats the best way to go. I'm going to start asking around for some quotes but already I think I've got a couple ways to go and wondering other opinions.

I could go for just new machines and hope it's just the spec of the machine that's causing the issues & upgrade the Cubase software to correct bugs within that.
A new domain ring fenced for Music with its own server for shared docs and user managment.
A Mac suite either with Mac server or linked into the CC4 AD.

Any tips, suggestions would be greatful thanks!