Built mine over a year ago now.
• Intel Core2 Quad Q9450 (2.67GHz) w/ Zalman 9500 heatsink+fan
• Gigabyte GA-P35-DS4 motherboard (based on the Intel P35 chipset)
• WinXP-x86, Vista-64x, Win7-64x tri-boot
• 2GB CAS5 Corsair DDR2 800
• 2 x 500GB Western Digital Caviar RE2 enterprise (for better reliability) hard-drives
• 512MB nVidia GeForce 8800GT. Great for gaming.
• Corsair HX520 (520W) PSU.
• Nzxt Lexa case.
Total cost ~£1K.
Solid as a rock with XP. Never had a single blue screen on this computer.
Vista created DPC spikes when I first tested it for audio work, but I think this was due to early graphics card drivers at the time but I've not since tested it in over a year as XP just works so well.
Not tested Win7 for audio yet, but it's much faster than Vista in general use.
