[PLUG] Looking at distros for old desktops

[Arindam]

I have some aging / old desktops for which I am looking for
appropriate distributions. I intend to use them as developer systems
for some kernel development (noo-b there, modest intentions) but
prefer an X installation.

One desktop is a PIII 733 MHz with Intel 815e chipset, 512 Megs
on-board memory and 40G hard drive.
One is a P4 2.4 GHz with 1 G memory and 40G hard-drive.

1. Looked at Xubuntu for the lighter-weight XFCE and installed it on
the P4 box. Liked it quite a bit - my first *buntu box - so far have
only used FC/OpenSuSE. But, I want to hand pick packages that are
installed and all said and done that seems not so straightforward with
*buntus. Am I wrong there?

2. Are there Gentoo users who can tell me about their experience with
Gentoo. Is it too much of a bother in the long run to perform software
upgrades?

3. Any other lightweight but not too minimalistic distros?

Thanks.
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* I am not sharing disk space with skylights, casements, window$ or
immovable furniture of any sort.