My PC - Custom Built - by me. Won't buy a branded PC, as a tech I prefer to build my own. I personally recommend having a custom PC built if you can afford the initial outlay as it will be built to your requirements and not be some marketing guy's idea of the perfect home PC.
Also, custom built PCs tend to be cheaper and more reliable than branded PCs (every custom PC I have built for customers is thoroughly tested for at least 48 hours after system build to ensure there a no software problems or defective parts).

My System Spec :-
CPU - AMD Athlon XP 3200
Memory - 1GB DDR Ram
Motherboard - Gigabyte GA-7N400 Pro2 (On Board IDE RAID, SATA RAID, Gigabit LAN, Firewire, NForce2 chipset (supports Dual Channel memory)).
Graphics Card - 128 Mb Geforce FX5200
Hard Drives - Primary Hard Drive - 120 GB Western Digital.

• Secondary Hard Drive - 160 GB Western Digital.
  DVD Rewriter - Pioneer DVR-106D 4x DVD -R -RW +R +RW.
  CD Rewriter - Philips PCRW5232P 52x 32x 52x.
  Operating System - Windows 2000 Pro - Don't like the 'kiddified' Win XP.
  Poser Version - Poser 5 patched to SR 4.1