You can use about any Windows CE driven handheld. Some of the newer ones have a built in 802.11b so as long as you configure it to your home network, there is no extra cost. (Just unit cost) I bought my iPAQ on ebay for $225 last year for a HT remote and use it for everything now.
Speed, I couldn't say. I use mine through the USB cradle, but it is pretty fast for a 200, 300 or 400 mhz PXA250 scalable speed processor with 64mb RAm/32mb ROM (512mb RAM currently NOT in exp slot).
Mine took just under 55 seconds to load msn homepage for the first time(shuttle graphics and all). It will load a satelliteguys page of threads in about 5 seconds and Cascade's image attachment doesn't show up in the PDA version.
You might think 55 seconds is a long time, but it has to go from:
PDA-CRADLE-USB-COMPUTER-zonealarm-Wireless Lan Card- Wireless Router-DLS Modem-ISP-WWW-and back again.
Like I said, *text only* loads super quick.
Plus it will keep my appointments, adresses, play mp3's, wma's and remind me to put it back in the cradle when it gets low on juice. (as long as I remember to do it every few days)
Thats it. There are a BUNCH of different handhelds and even small tablet computers out there. I was going to get a tablet until I heard about the Archos AV700 series coming out. (Portable Media Device)
Who knows... I have to spend my pennies wisely...