I am currently 9since the day before yesterday) using LXDE desktop. It is
quite comfortable and lightning fast.
Another thing that I experimented with but then abandoned was a combination of
Fluxbox or Openbox and then launching either nautilus or thunar or from the
command line. Sometimes I used pcmanfm. I got back to Gnome+Compiz-fusion but
from now on I will keep using LXDE for most of the time. I like it very much.
To me Gnome seemed to be a little slow even at 1512 MB of RAM an 2.66 GHz
processor.
LXDE is faster than freshly installed Windows XP.