where's my serial number?

Ok, maybe i shouldn't have trashed the email Cycling74 first sent when i bought Max/MSP5.......I didn't know it contained that one piece of info that is now so vital. And it's not on the MyAccounts page either, that section is just blank (I bought a download of Max/MSP5). Does it live in the Windows registry anywhere (Vista SP1)?
many thanks
............twenty minutes later.....................
ps how do you delete posts when you've found the answer yourself???? (I found the serial number under 'All Transactions' as opposed to 'My Orders')