I have had a few message from people recently, one more today in fact regarding people mis-placing the SRP ID, Authentication Key or CAL Key but there is really no need to worry you can get a copy of the information by referring back to an email that was sent to you by RIM.
Open the mailbox which you registered your version of BES Express with, and look for an email with a subject header looking like the following:
BlackBerry Purchase Information - Order Reference Number ********
Within that email, you are provided with a link in which you use initially to obtain the above information and to download the BES Express Software, If you click on that link and fill in the first page as before and click on next, the next screen will show you the information you require.
Hope that helps,