This blogger tries Ubuntu in an old Inspiron 4000 laptop with 700MHz Pentium 3 and 310Mb of memory
Read how it went:
As I used Ubuntu, I could feel myself getting dismayed by just how much work I'd have to put in to get it “just right” for me. But then my XP setup has taken several years to get right, so expecting to get to the same point in a few hours is unreasonable.
So all in all I can imagine using this day to day. It's not quite ready for prime time as a direct replacement for XP but it's damn close. However trying to run it on 5 year old hardware is not really on. This is disappointing as I expected it to be at least as responsive as XP and hopefully better since the underlying OS is better architected. Something not exactly surprising was the font problem as I've heard of similar stories before and screen driver problem. It's a testament to how much work Microsoft have done, both themselves and with their partners that Windows screen and font control is excellent. It's only when you see another system fail that you appreciate it. This is perhaps the biggest issue that Linux has to solve before it can become truly mainstream. And I get the impression that this is down to the X code and not any one distro as they mostly seem to use the same underlying system. It's just possible that Kubuntu and Xubuntu (and hence KDE and Xfc) work better but I think the problem is actually below these in X.