What he said.
It will not support standard Retail FreeSpace 2...we've used some of the new SEXP's that come with SCP and a few extra goodies.
Frankly, all of the eyecandy on SCP right now kills my machine. So I have most of it turned off. You can run BWO with all of the fancyness turned off if you want and get the basic runnings...
We probably won't overhaul our weapons graphics as much as I was going to originally so they are still 256 color...and there are 256 color nebulas...the high color TGA's are MUCH better...but you have both as options.
So...you aren't forced to use super mega detail. Trust me.