Computer music server PC or Apple????

From reading several reviews it appears that Apple has the edge. I'm thinking of building a system with the following:

MiniMac with wireless keyboard and mouse
Iomega 500GB Desktop Hard Drive firewire
PS Audio Digital Link III USB
Cheap 15inch flat screen monitor

Does anyone have anything close to this?
Does the choice of the MiniMac make sense over a Laptop?
How loud is the MiniMac? Can I have it in the same room?
I plan to use cables and hard wire, not wireless.

Cost is an object but don't want to have to replace pieces in the near future.

Any feedback is welcome.