I was fixing someone's computer recently (a friend) and the owner of the computer was complaining about how slow it is. So I checked the system specs. and it had

(It was a Dell Dimension DE051)

It has an Intel Celeron CPU 2.8ghz
512MB of RAM
and around 90GB of hd space.

So I was thinking that I should put ubuntu on it using virtualbox (because they don't have install disk they only have restore partition which I do not want to screw up.) The thing is what type of linux os should I get?

I will probably giving the version of ubuntu 206MB of RAM. Now should I get

ubuntu
kubuntu
xubuntu

I'm just looking for an easy to use os for my friend. (Is kubuntu easier to learn because it only has one bar?)