With a question like that ,you're in for some heavy advertisement by several "Distro-Zealots".[
Given the info on your system , I'd say "Go Slackware" for it's damn complete for a distro , very light on your hardware.
Takes quite a bit of reading-up though , so be prepared to spend late hours , gazing at your monitor.
One convenient PRO : Their official forums are on this same site.
Good luck and if you manage Slackware:
and their friendly forums