After becoming familiar with hardware through troubleshooting various issues with my own and other's computers, I decided to take the plunge and build my own about three years ago.
The difficult part was deciding on a motherboard. After that, the hardware is pretty straightforward, and depends largely on budget and intended use.
My current specs:
CPU Type AMD Athlon 64, 2200 MHz (11 x 200) 3500+
Motherboard Asus A8V Deluxe
2 GB Kingston DDR PC 3200 (4 x 512)
Video Adapter NVIDIA GeForce 6200 (256 MB)
Disk Drive WDC WD30 00JB-00KFA0 USB Device
Disk Drive (2) Maxtor 6 Y080M0 SCSI Disk Device (80 GB, 7200 RPM, Serial-ATA/150)
Disk Drive Maxtor 6B160P0 (152 GB, IDE)
Disk Drive Promise 1+0 Stripe/RAID0 SCSI Disk Device (114 GB)
Monitor SyncMaster 226BW(Digital) [NoDB] (HVFP106136)
Printer HP DeskJet 812C
DVD Drive SONY DVD RW DRU-720A
CD Drive LG CD-ROM CRD-8400C
Floppy Drive Floppy disk drive