I have access to a MacPro and my parents (family computer) and it's fast! Has plenty of space for upgrades too, I think it has 8 slots for the RAM for example. We have 4 x 1Gb RAM sticks.
The cost of these PowerMacs / MacPro's are expensive but you get a very very powerful bit of kit!
I've always had issues with anything that has something else built into it. TV/Video combi, TV/DVD Combi, DVD/VHS combi and so on and I'd hate to fall into the trap of having a broken display on an iMac stopping me from using the computer within it. Main reason for opting for a minimac and the cost of a PowerMac. Although I will upgrade to a PowerMac when finances are not so tight or if my Mac should ever play up ... No signs of that so far
