I did in the past.
My first PC, bought in May 1999, was Pentium II 233MHz with 32 MB RAM, 4 GB HDD 7200RPM and some internal GPU, 15" monitor (with resolution of 1024x768 in 85Hz, I still have it and use it as a second monitor). I have upgraded that PC twice, the first time I purchased Voodoo 2 3DFx 12/16 MB VRAM. That GPU was amazing. The second time I bought additional 64 MB RAM, resulting in 96MB in total.
The second PC I've got, in 2002, was AMD, probably around 1.2-1.5 GHz, 512 MB RAM, 80GB HDD 7200 RPM and GF4MX 64 MB. I used the same monitor and speakers from the old PC. I don't think I've ever upgraded this one.
The third PC, which I got in 2005, was a 14" (1280x768) notebook, AMD Turion 64 1.6 GHz, 512 MB DDR 333 MHz RAM, 80 GB 4200 RPM HDD and internal ATI RADEON XPRESS 200M (shared memory 128 MB). Shared memory made the actual RAM to be 384 MB, so soon after I have bought 512 MB RAM and replaced one 256 MB, therefore I had 768 (128 VRAM and 640 RAM). Some time later I still wasn't happy with the memory, so I bought 1 GB, making it 1536 (minus 128 for VRAM).
The next PC was desktop again, purchased in 2007, but I cannot remember exact specifications. It had 2GHz AMD CPU, 2-4 GB RAM and Nvidia GT(X?) 6800/6600 with 256 MB VRAM. No idea what HDD it had, except that it was standard 7200 RPM. I bought a new 22" monitor with 1650x1050 resolution.
Then I had two old and used small (12-13")laptops for old games. One was IBM with a pre-pentium processor, 32 MB RAM, but it broke. So I bought Panasonic Toughbook CF-71 for about 50€. It has Pentium II 300 MHz, 96 MB RAM and NeoMagic GPU with 1 MB VRAM, 1024x768 resolution. It had 2 GB Hard Drive, but I replaced it with 80 GB 5400 RPM, so I could store all these old games still worth playing. The laptop still works as a charm.
The latest PC I have bought is a 15" (1366x768) 2009 laptop I use right now. Core 2 Duo 64 2.1GHz, 4 GB DDR2 800 MHz RAM and ATI Radeon 4650 1GB VRAM, 320 GB 5400 RPM HDD. I've never upgraded it, excluding buying Windows 7. So far I never felt a need to and I still don't. Thanks to consoles all the new games still work fine, at worst on low details, but as long as they work I'm happy. I see myself still using it for a long period of time because my financial situation went downhill since 2009 and I won't be able to buy a new PC for quite a while, however, to be honest I don't really care. As I said, everything works, even if in low details and 20 FPS (but that's just ArmA3, the rest of the new games run much better).
EDIT:
As a bonus, my laptop models (except the IBM one):
2005, CompaQ Presario V2000:
,
CF-71:
(though I have silver version)
2009, Toshiba Satellite L500-126: