. If you have at least 1Gb of memory then whichever is your personal prefference from the list. If you have less, then consider choosing a light weight window manager. .
You could easily run something like Xubuntu using 256 or even 128mb. http://www.xubuntu.org/ You'll get updated packages, the best package managing system out there IMO (apt) and it's lightweight
You can boot Xubuntu and only assign 128mb of memory to it. Btw, you should check e-bay to see if there's any cheapo memory modules for your lappy.