I had a dx4-120. 100% constructed from parts I managed to mooch for free. Threw in an 8mb voodoo 2 to go with my epic 4mb matrox millenium gfx card and I was fragging/lagging away on quake 2 with my 28.8 modem in no time. I was also paying a fortune per minute to be online. Good times 
For first computer and not just PC it was a c64. The newer model which looked a bit like the amiga I really wanted. Had been tinkering with 'em ever since my brothers zx-81 with its totally overpowered 16k ram pack. He also had a c16, vic20 and a plus 4. Also good times 