I recently brought an Acer Veriton X270.
Ubuntu Linux 8.04 works well except for sound. Basic stereo sound output works, but sound input (microphone) and some advanced 3D and surround sound does not work. The front headphone jack does not work correctly either. (All this works in Windows, so it’s not a hardware problem.)
Apart from the poor sound support in Linux, I am quite happy with this computer. It’s small (though not super small like Mac Mini or Fujitsu ESPRIMO Q), quiet, has all features you need and works out of the box. And it has a compelling price.
An odd detail is that it has HDMI instead of DVI for digital video output (it has VGA too, but who wants to use that nowadays?). But with a cheap HDMI-DVI adapter, you can connect a regular DVI display.