Red Gate's SQL Compare will un-encrypt an "encrypted" stored procedure.
1) Start SQL Compare.
2) Specify the database , containing the encrypted procedure(s) , as both the source and target (can pick a different db if you wish as the target).
3) Click COMPARE.
4) In the results window, click on the stored procedure that you are interested in and BAZINGA..... there is the source code.
I was using version 126.96.36.1990 in case your experience varies. I was using SQL 2005 . I tried on SQL 2000 and it also worked.