not to get off topic but XP is going to have 64 bit support...(I know...something Macs have had forever!) but for us pc users it will be a massive difference especially with the Intel Itanium processors (64 bit as well...yeah I know...Macs have had if from day one!) coming out. As far as 95, 98, and ME go...there is not BIG difference...just more eye candy...something I can go without in an OS. No back to topic. Bryce 5 does offer many advantages. Metaballs for one. This shows that Bryce is actually starting to enter the modeling ring, other than basic booleans and the grayscale terrains and lattices. This is a MAJOR step forward for Bryce. Plus with the added Tree lab users can get more control over their vegetation rather than just downloading models and hoping that they work out. Plus with network rendering capabilities Bryce is taking a MAJOR step forward as well! This is generally seen only in the "big boys" of graphics (ie. Max etc.) I for one believe that the upgrade is worth the money. If nothing else the network render has me sold! Modeling I could care less about. I have carrara and 3DS Max for that. But I've gotta say...I just love the way Bryce renders! It is very distinct and has a wonderful elegance and warmth to it.