1. Got an old Compaq:
Originally, it was a 486 with 8MB RAM. Upgraded with an Evergreen Overdrive Processor to P66. Memory upgraded from 8 MB to 64MB. A 2.1GB Hard Drive added. It's slow as heck, but it still works perfectly. Even the 2XCDROM drive. Never had any reason to try Compaq's customer service.
2. Got an old Dell:
Pentium 200MMX. Matrox Millenium Video Card. Soundblaster 16 w/AWE32 daughter card. US Robotics (now 3Com) 33.6K modem. Not very proprietary. Now upgraded to 64MB RAM, generic 56K modem, Voodoo 2 Video card add-on, generic NIC.
The original 10X CDROM drive started failing after a year. I called Dell Tech support, and within a few days, a guy came out to my house and installed a 20X CDROM drive. The only problems I've had with this machine have been when I've attempted to add various NICs (ISA & PCI).
The Dell is still working perfectly. In fact, I'm using it to type this message right now. Certainly not as good as my home built system, but then it only took me a few hours to research what I wanted to buy from Dell. It took me MONTHS to decide on what to put in my self-built rig.
Bottom line: if you have the time and inclination to do all the research, shopping, and assembly, then building your own system is the way to go. Otherwise, you pay someone else to do it. That's why we pay car companies to build our cars, pay the doctor to take care of our health, and eat at McDonald's. Sure, we could do it better if we took the time and energy to do it all ourselves, but who actually could?