I currently use the 3500 and have two comments:
1) I much prefer the software and tv features of the ATI All-In-Wonder (I used the older rage pro version) over the tv tuner on the 3500. If you intend to use these features heavily consider the new ATI Radeon All-In-Wonder product.
2) The gaming I do is split between Unreal and Falcon. Falcon, like most sims, doesn't really benefit from the features developed for the last generation of cards (CPU dependent)and looks great on the 3500. Unreal looks fine to me, but then I'm not a hard-core 1st person shooter (and Unreal has a good Glide implementation). One BIG reason to go for the Voodoo is that it implements 3DNow better than most. So if you have an AMD chip, that might be something to consider.
In any case, buy the hardware that best supports the applications you intend to run. If you have older games and don't plan on upgrading your software the Voodoo3 3500 would be fine. The TV tuner and video editing features are acceptable. I am considering buying the 5000 when I build a second box simply because the anti-aliasing will improve the visual quality of the games I currently own and it will provide acceptable performance for the newer games. People argue about frame rates, but I really question whether you could tell the difference between 50 and 70 fps. My understanding is that human vision can't detect anything greater than 30 or 40 so I'm a little confused about the focus on FPS.