the credit has already been passed onto the affiliate via that link.. for instance, check out one of my old galleries:
http://refer.ccbill.com/cgi-bin/clic...kles.com/t/01/
when the user then visits the paysite on the same domain he has already been tracked...
a php solution if of course better so if you can spare a few bucks Ordo, go for donovans advice...