[ALUG] Installing Gentoo 2004.0

I've just downloaded the two ISOs for Gentoo 2004.0. Before I burn them to disc, does anyone know what they contain? Is it source packages or binary packages? And how long is it likely to take to install (from sources) a standard desktop system (X, KDE, OOo) on a Pentium III (512Mb RAM). Presumably I can do it a bit at a time (e.g. compile X first and then KDE in another session). What worries me slightly is that I'm running a laptop and they don't take kindly to be left switched on for long periods of time. Any thoughts would be very much appreciated. Cheers, Richard