I've been using Xubuntu on an old Dell
D600 Laptop for a few years now (since 6.06 version).

I tried other distros, and they seemed just
"too heavy" - Xubuntu performs really well -
on my laptop, with intel centrino processor,
768 mg Ram, 40 gig HD.

The xfce desktop, combined with Thunar file manager
is fast because it's lighter on memory requirements.
For even more responsiveness,
you can install ICEWM or Fluxbox and customize it by editing
specific text-files.

Likes:
Responds well on older hardware.
Synaptic pkg manager (just like other `buntus`)
Hardware detection quite good -including the wi-fi (I
did not need NDISWRAPPER -one less thing that I "had" to do.
-your mileage may vary, as this experience may not apply to all.

Dislikes:
With the 8.04 version of Xubuntu, the Network Configuration GUI
acts really flaky and I'm about to dump it.
If you are using wifi, I suggest Wifi Radar, or KWifiManager.

It's not easy (or maybe I've missed something) to have
separate background colors/pictures for each desktop.
A minor nuisance if you like to have diff bg colors for
different desktops. Xubuntu has all of your desktops
as the same photo (if you've set a photo) or same
background color or background art.

While the hardware detection is great, it didn't pick
up on the onboard video of the laptop and it
offers only a few video resolution choices. Not all
of them are bad, but I need to invest time to get
and install some ATI drivers. Again, minor,
since the Windows XP install (it's a dual-boot) didn't
either, I had to install it from a driver CD.


Overall, it's a good distro and I like it. It's fast,
highly-customizable, and is updated on the Ubuntu
schedule, with a highly-active user community.