Linux PDAs: http://www.pdabuyersguide.com/linux.htm

But, I'd suggest using a PalmOS based PDA, instead of Linux. The amount of software and ministry oriented apps is really helpful. current palms: http://www.pdabuyersguide.com/pilot.htm

If you need wifi, you can either get one with it built-in, or get an add on card. That'll be at least $300. here's some wifi reviews for pdas: http://www.pdabuyersguide.com/tips/wifi.htm