Converting text to html

[achrist at easystreet.com]

Is there any recommended code available to convert plain text into
text that can go into an html document without breaking it?  I 
think that I just have to do these three translations:

	< =>  <	> =>  >   & 	=>  &

But I'm not sure if there are any others.  I've got to do this 
quite a bit while the user is waiting, so it would be nice to
have something that did it in a way that was not a lot slower
than any of the alternatives.  

Surely someone must have cracked this nut sys.maxint times by now.

TIA


Al