Elive
The basic setup to get a daily usable device could be a Pentium 4 HT (or equivalent), 2gb ram, 30gb 7200 rpm sata hard disk and a graphic acceleration capable graphics card; the previous recommended requirements would still give a snappy  system, but they would not meet modern web browsing requirements (so the experience with Firefox or Chromium may not be the best), which is out of the os control: for that reason Elive also ships some low resources browsers like Netsurf and Links2, though they are unable to visualize every website correctly.