My trusty laptop has been trying to die for a good 12 months; bad hard drive sectors, faulty RAM and other annoying illnesses. Under Windows XP it had become massively unstable and would BSOD (blue screen of death) at regular intervals when the mood took it. I decided that it was going to be put onto Ubuntu for stability and security - hopefully getting more life out of it.
The best part about doing this (with any distro)
The main reason why I wanted to do this was that Linux tends to be more stable and won't crash in the spectacular and time consuming way Windows does. When Windows would BSOD Ubuntu will just ask me to log on again (as X restarts I guess) which is a lot nicer than waiting for an old, ill laptop to completely reboot.
Installing Ubuntu - Partitioning
I've always liked the Ubuntu installer, it's pretty sensible and the partitioner (Gparted) is an excellent implementation; it's certainly the best I've used by a long way.