Do you want/need to handle your affiliate program in-house through an affiliate software package - an alternative would be to go down the ClickBank, PayDotCom, PaySpree, Click2Sell and similar route and have it all done for you by adding your site/product to one of them.
Something to think about - advantages and disadvantages to both options and which may be best for you. Depends how "hands on" with it you want to be I guess.