Definitely upgrade to either P4 or P5. The difference is incredible. P5 is coming along, but it's still a bit slow. I really haven't played with the advanced features, like dynamic cloth or hair. It's the little things that make it great for me. Nested libraries rock! I can't go back to P4 simply because of that. (I have gobs and gobs of stuff.) Measurements in feet rather than Poser units is also great. P5 uses .jpg files for bump maps and doesn't need to create .rsr copies of the .obj files so it really cuts down on hard drive space used. (I saved over 1/2 a GB in space by going with P5 and nuking unneeded files.) The one advanced P5 feature that I love is the Material room. There's some really great effects you can get with that. The P5 render engine is getting faster, but it depends on what settings you use. The P4 render engine in P5 is faster than firefly (a.k.a. stoned sloth), so you can pretty much have your cake and eat it, too. That said, I still think P5 is too slow in rendering sometimes and there's been a few pictures where the shadows seemed odd. With SR-2.1, P5 has been stable for me, and I was one of the people with a lot of problems with the program. I still wouldn't pronounce it perfect, nor recommend it for everyone, but it's up to 1 1/2 thumbs up from me. Hope that helps!