This is the second time i've got to mention this today.
Arch or Archbang. Use openbox. This keeps it to about 20M of memory.
If you do something like use Chromium or Firefox, expect it to eat up quite a bit of ram. I use 'dwb' which is like a browser built on vim that i Love. http://portix.bitbucket.org/dwb/
At most i consume 80M of memory with dwb, openbox, terminals, wireless and irssi. I havent seen my cpu use go over 20%.
And this is on an old compaq that seriously speed-wise puts any of my exec's macf()ck airs to shame.