Weeeeell, I'm notorious for giving people WAY 
too much time.  Don't wait until it's too late 
to send a second chance notice.

I guess it just depends on how long it's been 
since he contacted you (is that the two weeks or 
has it been two weeks since the auction 
ended?).  If I were you, I would insist on 
Paypal within the next two days or just consider 
the transaction null and void (don't threaten 
negative feedback, that usually just pisses them 
off).  If he tries to pay with a money order 
after waiting this long, he's probably just 
fishing for more time.

Sorry!  E-Bay woes suck!