Using an old Medion Laptop from AD2003 ,with P4-2.4GHz CPU and just 512MB
RAM, I recently upgraded Lubuntu 10.04 to 12.04 . Running well ,be it
somewhat slower than 10.04

Ubuntu 12.04 won´t run, having a more heavy desktop.

Lubuntu 12.04 ,supported up to April 2017 (I hope) will probably be the
last Linux distro to be used on this hardware , meaning a possible life
span of 14 yrs ............not bad for a medium priced laptop (donated
to me in 2006) .