I thought it might be useful to add a bit more about how it's going with Ubuntu.
Overall I'm very impressed with this distribution - it is very polished and easy, and yet it has all the technical merits of Debian. Other user friendly distributions often do Bad Things and remove choice to simplify the work of the distribution creators. Debian always has nice secure defaults, and being more of a 'meta-distribution' it is always flexible and never limits your choices.
I have had a few problems, mainly to do with running the AMD 64 version I think:
I can't run Win4Lin. I had to build my own kernel (which was very easy thanks to instructions on the Ubuntu Wiki). However, the Win4Lin installation didn't recognise I was running a patched kernel, and looking on their website I discovered this is a straightforward limitation of AMD 64 chips with 64 bit OSes (Win4Lin ran fine on my i586 Mandrake install on this machine - so it looks like I'll be keeping that installation around)
There is less software available for AMD64. All the core Ubuntu stuff is compiled for AMD64, but some user contributed stuff (like libdvdcss) is missing - I did find one eventually on debian.video.free.
Kaffeine (media player) is crashy. It will play most things, including DVDs perfectly, but afterwards it will routinely crash. If I try to open a second playlist, it will crash (perhaps it's a message). Some other apps seem to be showing this kind of behaviour, so it I'm guessing this is an AMD 64 issue as no-one else is reporting problems. I also get a crash dialog from an 'unknown' application fairly regularly. As you can guess, I have no idea what is causing that! According to a recent article on the state of 64-bit and Linux, there are still a fair number of issues to iron out with running 64-bit OSes, so it's not surprising I'm having some problems.
Oh, one tiny glitch with hardware detection that can make a big difference: hdparm, a program that tunes IDE drives for higher performance, doesn't seem to be run correctly or automatically for my CDROM drives (though it works for my hard drive). I have to do hdparm -d1 /dev/hdc /dev/hdd to get proper performance out of them.
Looks
Did I mention that Ubuntu looks just great? It does. Both the GNOME and KDE desktops look fabulous (in their different ways). I'm using the 'lipstik' theme on KDE which is rather nice.
I've discovered some sites that show off Konqueror's superiority as a browser. Have a look at the drop shadows on the Ubuntu home page on this screen shot – it does add a nice touch that even Firefox users don't get – only KHTML browser such as Konqueror and Safari supports them at the moment.
That's all for now.