People seem to remember pc prices incorrectly. In 1995 I paid about $800 AUD for a Pentium mmx 200 + 32meg ram, 8 meg diamond viper video card, sb16, etc. This was much, much faster than an '060 based amiga and cheaper as well. Having said this I still enjoyed the amiga more, but I thought Id mention it seeing as people are quoting ridiculously innaccurate prices. Now as for longevity, that's aso a crock. A person simply needs to run software suited to the specs. Would someone expect to play amiga quake on a stock a1200, or would they instead use software that works well on thier machine? A p200mmx is still more usable (in terms of performance) than any a1200... again, a person simply needs to chose appropriate software for the hardware (as with any computer, amiga included).
The whole "need to upgrade, bin, buy new, etc." to keep using a pc is complete BS. Sure, it dates quickly compared to amiga gear, but that's simply because PC gear *did* advance constantly. A pc didnt become less usable simply because there's constantly faster gear out there.
Now as for Doom,... I cant agree with people here. Doom rocked. Still one of the best fps games out there. Well designed levels, great enemies, great weapons. It was more than a well crafted bit of code, it was a well crafted game.