Depends on what you want to do and spend. To play outside you'll need at the minimum an airport base station (you could probably get away with linksys wireless/router basestation, just haven't done it myself) and an iBook with Airport card. The iBook goes for about $1200 for a 12" screen, $1500 for a 14" screen. If you have the money, go for a Powerbook G4 with the 15.2" widescreen (it's worth it) starting from $1995.
Myself, I now have a Powerbook G4 667/512Mb RAM/30Gb HD/CDRW+DVD + Airport and love it ($2995). If you need MS Office 2000/XP compatibility, MS produces a Mac version that is file compatible and then some. I can also access my Windows boxes across the lan (wireless or wired). With a 5+ hour battery life (theoretical, haven't ever used it that long off of AC mail) it comes in a nice 5.4 pound package that includes built-in 56K modem, 10/100/1000 ethernet, 2 USB, 1 Firewire (iLink, IEEE 1392), S-Video, and XGA output.
All in all, I left Wintel for Apple about 5 months ago on a lark and haven't looked back. I can do everything I did on a Win/Linux dual boot Dell Inspiron 7500 with my Powerbook at almost half the weight and it doesn't burn my lap :)