3d limits for machine spec

I need to make sure my game will run at a decent resolution (e.g. 1024x768) on fairly old hardware... I'd like it to run well on Geforce 3 Ti-200 and above. I know some people aim stuff to run well at 800x600 on a GF2.

Is this a good minimum spec to aim at?

What kind of limits on polys / textures should I be looking at? I know this varies wildly depending on who you speak to, but is 100k polys and say 20 hi-res textures in one scene ok?

I'd be interested in hearing the experiences of people who have games out there, and have had them tested on a multitude of low-spec hardware.

I would say 60K polys and 20 high res textures @ 800x600 on a gf3ti200 would be a good target to aim for.

In a little test app I built the gf3ti200 was getting around 38-40fps with 77K polys in view and some fairly strenous collision detection going on. Same scene on my main rig (5950ultra) was getting well over 100fps.

(this little test has about 10x 512x512 textures and a couple of 2048x2048 ones)

unfortunately its not as easy as it seems, there are many more things to consider like motherboard bottlenecks, drivers, ram in the machine, processor speed.

For example: a GF2 on a 500Mhz processor will not be as good as a GF2 on a 1Ghz processor

Unfortunately writing for specs is a pink elephant, its easier to write the complete game then add switches to turn off effects that are 100% needed but make the game look nicer. That should allow it to run on lower specs machines.