I've tried both Lubuntu (LXDE) and Xubuntu (XFCE) which both use
faster, lightweight window managers but, as with gird, I didn't
especially like the file managers - much prefer Naulitus, but that's a
personal thing ...

If you're a gnome (2.x) fan, you may get on more with Xubuntu, as XFCE
is GTK based, same as gnome.

One point to take into consideration, if you're looking at Ubuntu
11.04, the full-blown install will default to the Unoty desktop,
rather than gnome 2.x ... you may need to install this seperately
(despite suggestions that it's still there as a fall-back - I've not
found this to be the case, and I was only upgrading, arther than
cold-installing!). A lot of new [gnome-based] distro's (such as
Fedora) are also now using the gnome 3 desktop, which differs
considerably from gnome 2 ... Ubuntu-based Linux-Mint, however,
retains the familiar gnome 2.x.

I've been happily running (full) Ubuntu on an Acer Aspire One netbook,
for quite a while now, without too many problems ... just so long as I
respect the hardware limitations, and don't try to run too many things
concurrently ...