The best part is using my Treo as a modem. I signed up for Sprint's EVDO data plan which enables the Treo to use their hi-speed network. I can access any of my pop/smtp e-mail accounts (three so far) and download all my e-mail directly to the Treo at comfortable speeds. The modem feature is awesome and it is the perfect accessory to the Tablet PC. I can go anywhere, leave the Treo in my pocket, log into my Tablet PC and be on the internet in seconds-- all over the bluetooth connection and NO cables. I'm finding that the speeds are excellent but they seem to vary probably because of network strength and bluetooth.
I used DSLReports.com to give me an idea of the performance using bluetooth on the Tablet PC and I am somewhat relunctant to publish the numbers here. There are so many variables and I'm not performing a controlled test. Perhaps there is a better way to test connection speed and I welcome suggestions. But for now, I can say that I've ran dslreports 5 times tonight and each time I got widely different values ranging from 78kbps to 224kbps on download speeds and 57kbps to 64kbps on upload. I was a little surprised at the 224kbps since that seems too good to be true especially since my connection is over bluetooth. My signal strength was 2 bars. So, more tests are needed. In any case, my internet connection "feels" fast enough and I was able to browse the internet and do anything I normally would do if I were connected to my cable modem at home. By the way, as a comparison, I usually get around 4700kbps/360kbps on the cable modem.
I'll post more info about the Treo 700p later. If anyone is interested in getting one, I'll have to relate my 2 hour ordeal at the Sprint store trying to get the discounted price (about $400) and the family plan with modem. For some reason, the store people were not able to bundle the modem plan along with the family plan (2 phones sharing minutes- other phone was a standard samsung flipphone). A Sprint rep that we called on the phone from the store was also convinced that a combo was impossible. I left the store with the family plan and no modem plan. I waited a day, called Sprint and one of their Treo specialists was able to add the modem (but it was a struggle).
So far, I am very happy with the Treo. Now, where is my bluetooth headset...