"My" first PC that I actually built was a (Gasp) Cyrix P200+ with 32MB of SDRAM and some crappy generic motherboard. I had a 4.3GB Quantum Bigfoot hard drive, an 8x cdrom drive, a 4mb S3 Virge video card, a 14inch CRT moniter, an IBM Model M keyboard, and a Microsoft PS/2 mouse. I had a zoltrix 33.6k modem. I also had a Sound blaster 16 clone.
Before that I had a 486 that I got for free since someone was throwwing it away. I used the Keyboard and Monitor from the 486 for many more years.
I was 16 at the time, and a complete hardware noob. My build was < 1000, and this was before the days of the sub 1000 PC, so even though the CPU was a steaming pile of crap, I made off OK.
It played Duke Nukem 3d and Total Annihilation quite well. My friends P133 was faster for games, but the Cyrix held it's own and usually came out ahead vs another friends P75. About 7 or 8 months after I built the box, I shelled out a few more bucks and Purchased an AMD K6 233 and a new motherboard. It was MUCH faster and more stable then. Once I picked up my Canopus Pure3D 6MB 3d accelerator card ... the box SCREAMED in Quake.
I kept the K6 233 as my only box for a couple of years. It played everything great up to and NOT including Half Life. Halflife was a slideshow.
When the Celeron 300a and BH6 deals started showing up ... I again upgraded .... But that's not my First PC, it's just my first real "performance" PC