Possible, but if he removes the link from his logs (browser history or MSN chatlogs), I doubt he kept it. He might also just be able to have it pulled from the net. But, something gives me a feeling that OP put a rat in his Crypter -- maybe the guy found out and charged back? Although, he acts like he doesn't know so that theory isn't exactly... Meh
@OP, how DID you get a virus on his computer?
Exactly. Any smart person wouldn't download any program of a guy they just scammed.