Oldsmobile_Mike:
I have been using Pegasos 1 with 128MB of ram and it's been my main-system since August. What I have seen is that 128MB is quite enough for normal use. In my case using high resolution screens (1600*1200 truecolor) does eat considerable amounts of memory.. But it's no show stopper and with smaller Res it's not a problem at all.. But on Pegasos 2 I'm getting either 256 or 512M ...

For CD size.. I seem to remeber that Mos1.4 CD-image is bit under 40 Megabytes. That contains a lot of contribution stuff like background images, icons, all stuff from Vapor (Voyager is regged, other ones are demos).
At hard disk... Mos system directory: has about 17megs of stuff. and I could easily get it at least couple megabytes lower cause there are files I don't neet atm like extra TP-dir printer drivers, Datatypes, Grafix drivers for Voodoo/Sis/ Perimedia, Gui Skins.