jpm1999 - perhaps you can benefit a little from my experience. I decided last winter to build a new machine that included XP/Pro. One objective was to build a machine in which Vista would work without apology. Also, I wanted to do some video and audio editing. And I manage about 20 websites, so I needed something that would allow me to do multiple tasks and would make PhotoShop run like a rabbit. And I wanted quiet, and I wanted cool.
Case size was not an issue, so I selected the Cooler Master CM Cosmose 1000. It is a big and heavy (35# empty) case with two handles on the top to aid in moving, and a skid on the bottom to aid in sliding. To that I added the Cooler Master "Real Power Pro" 750w power supply that is certified "80 Plus".
My motherboard is the eVGA nFource 780i, which supports a wide range of Intel chips, and had on-board support of RAID-1 and RAID-5 disk arrays (more on that later). I chose the Intel Core 2 Q6600 processor, and have not been disappointed. I have a few software packages that implement multiprocessing, and it is nice to be surprised that my Mozy backup is completed when I didn't even know it had started. The processor can be upgraded with this motherboard and/or overclocked if needed (the case has enough cooling for that configuration).
I have a drive "C" and drive "D" hard disk ... the system/program drive C consist of a pair of WD Raptor X's 150GB drives in a RAID-1 array. These spin at 10,000 RPM. I suppose I could have sprung for a pair of 15,000 RPM drives, but I kept one eye on the budget. My data drive is a pair of WD Caviar 500GB drives also in a RAID-1 array. Applying 20-20 hindsight, I now wish I would have installed another drive in each array and gone with RAID-5. Perhaps I?ll do this - but in 6-8 years, when I do this again, everything may well be solid state and I will not have rotating memory. We'll see.
To all of that I added a floppy disk drive that includes a bunch of flash memory card sockets, a modem (which I've never used), and a DVD/CD-ROM reader/burner, plus and OEM version of XP/Pro.
Finally, the case is heavy (I have upper body strength problems) and I was in a hurry and otherwise engaged with my work, so I had a local shop assemble and burn-in the basic system ($200), so all I had to do was add my application software and data.
I'm very pleased with the result. Cost was about $2,600. You can do it for about half the cost (or less) if you start eliminating things (RAID, drive D, less expensive case) ? your choice.
Good Luck !!