I've never built my PC from scratch (I've done it with other PCs, but not mine).
Mine's been evolving since it was a 33mhz 486 w/ 8mb of ram and a 400mb HD.
Fist upgrade was a 66mhz DX2 chip.
Followed that w/ a motherboard and 166mhz CPU. Needed new ram for the new board, so I picked up a 66mhz SDRAM DIMM for it. 32mb.
After that, Igot a 4gb HD.
Machine was much snappier now, but then quake 2 just came out. I bought it. It was slow.
I was guessing it was the fault of my 2mb ISA video card.
Picked up a 6mb Canopus Pure3D (voodoo 1 card).
Ahh.... much better
the game still had a tendancy to load slowly. 64 more MB of ram for me.
After that, the next upgrade was another now mobo/CPU combo. Was up to a 350mhz K6-2. oh, and this mobo had an AGP slot
When half-life came out, I bought it the first day, and a shiny new 16MB TNT card to go w/ it.
After that, I kinda lose track...
Since then, I've been through at leat 5 motherboards, seven processors, 5 or 6 hard drives, at least 6 video cards, a couple sound cards. 2 dvd drives, 2 CD-R drives, 3 or 4 CD-ROM drives, 3 monitors, at least three cases, 2 keyboards....
hell, a lot of stuff.
The same machine, now at version 473.21, is now an Athlon XP 1600+ w/ 80gb of disk space, 256mb ram.