You need at least 4 megabytes of memory in your machine. Technically, Linux will run with only 2 megs, but most installations and software require 4. The more memory you have, the happier you'll be. I suggest 8 or 16 megabytes if you're planning to use X-Windows.
How the times have changed...
@vaporeon_ emacs used to be infamous fur its memory hungriness, greedily taking up your 8 megs
