I use my mac mini for all my daily tasks ( surfing, email, chat, pictures, etc. ) and the only reason I keep my pc around is for playing cs. Tiger is the new version of OS X. My mini started it with 256MB and it was definatly not enough (before or after the upgrade to Tiger) so I upgraded to 1GB. I would definatly recommend getting the ram upgrade up front as installing it was a pain. The airport card is a built in wireless card.
As for the nay sayers you can talk crap about the Mac all you want but I would take it over my windows box any day of the week. Its small, quiet, and it just works.