I run a commercial recording studio in Sydney Australia, using Avid/Digidesign Pro Tools hardware (This involves three PCIe cards with specialized DSP chips). Over the years I have sunk an outrageous amount of money into Apple Mac Pro systems, and frankly I am sick of it.
My business partner is of the belief that "no PC system can match the Mac for performance and reliability". I think this is utter nonsense.
The thing that Macs are famous for is their user friendliness. When you strip back a Mac to it's core structure, all it is essentially is a stripped down version of Linux.
So what I've done is built a PC with as close to the Macs specifications as possible. The only major differences is that you have 2gb more RAM than the Mac (Apple special orders theirs) and that the motherboard choice is very limited for two CPU's.
Here it is:
CPU: Intel Xeon X5650 Westmere 2.66GHz LGA 1366 95W Six-Core Server Processor *2= $2007.98
Ram: 1x8gb ddr3 1600 Mushkin Enhanced Silverline= $94.99
Motherboard: EVGA Sr2 dual xeon motherboard= $579.99
GPU: SAPPHIRE Vapor-X 100283VX-2L Radeon HD 5770= $119.99 (quietest 5770 still available easily)
Heatsink: Corsair H40 closed loop watercooling *2 = $149.98 (should be near silent)
PSU: CORSAIR CMPSU-750TX 750W= $129.99
HDD: HITACHI Deskstar 1tb drive= $129.99
Microsoft Windows 7 Professional SP1 64-bit - OEM= $129.99
Case: LIAN LI PC-Z70B Black Aluminum ATX Full Tower Computer Case= $339.99 (The second cheapest Hptx motherboard size compatible case, very high end brand)
Extra fans to keep the noise down:Scythe SY1225SL12SL 120mm "Slipstream" Case Fan *5= $49.95
Subtotal before taxes and shipping= $3732.84 USD
Mac Pro total before taxes and shipping= $4999.99 USD
The Mac would be a good choice if you're looking for a warranty or ease of use. The programs you listed will run on a PC, but I'm not sure about the custom cards you have. I know nothing about them so I would email the company that makes them and see what they have to say. I *CAN* make this build cheaper, it's just rather late and I only did this because you wouldn't have gotten an answer otherwise.
(Can I have a free CD
(Feel free to ask any thing you need clearing up)
Windows gives you the ability to do more with your computer, but leaves you the ability to play with things you shouldn't be playing with. If you know what you want to do with you're OS, everything's fine. The only thing I have on my Mac is MS Office and Firefox. Keeps me from getting sidetracked.