I have the same video card that you have and I haven't had any problems with Poser 8. I'm running at 2.5 GB RAM and 2.8 MHz.  I'm also using XP.  So far I haven't had the same problems that some others are having.  Poser 8 is totally different than Poser 6,7, and Pro.  Unlike before where there wasn't much of a change Poser 8 can be considered a new version and not a 6.5 or 7.5 version.

I didn't have any problems installing it and I've done that 2 or 3 times and each time it was a clean install. I haven't had any library problems either. 

I enjoy Poser 8 and it has helped me to create better renders.  I don't have to use tons of light settings because of the improved lighting.  Would I recommend it? Yes.  I also have Poser 6 and I can tell you that Poser 8 is much better.  Does Poser 6 still have limited undo?  I have a review of Poser 8 on my site Poser By Design if you are interested in seeing some of the other things I've experienced with Poser 8.

When buying software be sure to buy according to your needs. What are the needs that would require you to buy a new Poser software?

Frederick
Poser By Design