I am attempting to identify handheld devices (PDAs) and rugged tablet
PCs and their components that can be used in a corporate wireless
environment.  The devices will be used to access back-end databases
via a proxy server (we have middleware already in place to handle this
part).  Our local network environment supports WIFI (802.11b) access. 
Both the handheld and the ruggedized tablet pc must be able to:
  1) support WIFI(802.11b) and WWAN (may be GSM/GPRS/CDMA/EDGE/EV-DO etc).  
  2) have full qwerty keyboards.  
In addition, the handhelds must also: 
  a) support touch screen applications - to this end they must have a
stylus pen for activating drop-down menus and such
  b) have at least 64 MB memory 
  c) have either Windows Mobile or Pocket PC OS and, 
  d) be compatible with Verizon, AT&T, or Cingular networks.  

So, I'm looking for examples of devices that meet these criteria. 
Especially appreciated would be devices that "do it all" and are
inexpensive!  After a bit of searching myself, I'm aware that separate
cards might need to be purchased (I think they're SD cards?). 
However, I'm utterly clueless as to how the various cards work with
the myriad of devices available.  Thanks!