The guy is spouting shit, to put it honestly. The single core AMD chips will NOT out perform the Core 2 Duo chips. The Core 2 Duo is a superior chip. There are dual core mobile Athlon chips and they’re ok, but I think as of right now Intel has them beat. This guy is your typical, “I think I know everything” computer guy. I’d be very very weary of having him build a “custom” laptop. What’s his warranty on his work? Are parts covered? Tech support? I build my own computers for myself, but I would never build a laptop. I’d prefer buying one.
Oh and as for media center and xp pro, the only and I mean ONLY thing that Media Center cannot do that XP Pro can, is join a domain and you can registry hack Media Center to join a domain if you want to.