Internetworkers: http://www.ibiblio.org/internetworkers/

[Corey Wilson <corey_wilson AT earthlink.net>]

FWIW, you can disable the automatic creation of hyperlinks in Excel XP 
from the tools menu, Autocorrect options.  If you are stuck with an 
earlier version, here are some workarounds I've found useful:

1) If you type an apostrophe at the beginning of the cell entry, the 
text will not be converted to a hyperlink, e.g.,
  'user AT company.com ==> user AT company.com (in plain text w/ no hyperlink)

2) If you screw up and forget the apostrophe, just hit undo (ctrl-z) 
after the hyperlink has been added.  This removes the hyperlink without 
otherwise changing the entry.  In fact, all of Microsoft's 
AutoCorrect-ions can be removed this way.

3) If you get a document with hyperlinks already in it, you have a few 
choices:
  a) right click the cell and choose "hyperlink -> remove hyperlink" 
from the menu.
  b) enter the cell using the keyboard and copy the address out of the 
input area
  c) enter the cell using the keyboard, hit F2, and use Shift+left to 
select the text

Disclaimer: I'm not sticking up for MS in this regard - I hate this 
"feature" as well.  But I am forced to use Excel from time to time, and 
I have spent a lot of effort trying to figure out workarounds.  My 
personal favorite is (3c), because you don't have to use the mouse...

Hope this helps,
--Corey