Hmm, well, do both. The games performance on the PC depends more on the GFx card, wich loses value VERY quickly. I'd advise you to not spend big money on the PC, you'll be very dissapointed within moths:)
An Amiga with that spec for that price?! Go to the 2nd hand market on the net, there are great deals sometimes. Have the patience and you'll get one.
Or wait till OS4 is out and get a PPC machine to go with it.. Now that would be a killer ugh? I think in the end it all depends on if you're doing it for needing it or pleasure. In either case it still depends on you. There are people still using Amigas professionally that prefer its characteristic features. If you can join fun with professional necessities, why not? Personally the thing I most like about the Amiga is multitasking and the responsiveness of the OS. Windows sucks in that respect.
