I dont think it that great of a deal. Don't get me wrong the offer is fair, but I wouldn't sweat not getting it as it doesn't look that great.
It is a 2GHz P4 not a PM laptop, that was new back in like 2002. I got the laptop in my sig about 3 months ago for $420 (without a HDD) and it was just over a year old at the time (I bought it 16 months after original purchase according to Toshiba).
I was also looking at the 9100 when I got this one and I was determined that $400 would be the absolute most I would pay for a 9100 on ebay and still feel that I got a good deal (assuming everything worked on it). But I could see $419 beeing ok considering it does have a 40GB drive and 1gb ram.
What makes you think he'll only take western union? the auction says that he prefers paypal. Anyways, the guy has 99.6% positive feedback on over 2600 transactions, the first three of which are for powerbooks. No negative feedbacks in last 12 months but over 840 positive int he same period. Point is since he's not selling 99cent pairs of socks por crap like that I think he's on legit and I would not worry about the western union thing.