Ask yourself some basic questions as to what you want to achieve with the PDA. I gather you are looking for connectivity with your laptop etc.
If you want Windows OS(handheld Word, Works, Excel etc), synchronisation with your laptop/desktop, inbuilt modem, keyboard etc consider the Jornada 720. It has one of the best screens in the business with both keyboard and "tap" capabilities. Yes it is a bit expensive but try buying it at an airport for some serious savings. By the time you add all of its capabilities to a Compaq IPAQ or Jornada 568 you would have easily passed the Jornada 720's selling price.
There are alot of serious choices out there. It still all depends on what you REALLY intend doing with the PDA. Be honest with yourself as this is an expensive decision.
Now how do I do that again .......