Just wanted to post this in case someone else finds it useful. Unfortunately, T-mobile reps incorrectly insist you cannot open the Android Marketplace without a data plan. Searching on the topic brings up lots of uncertain older posts
I bought a new HTC MyTouch Slide off ebay. I already have a Tmobile account but did not want the data plan. I connected to my home WIFI and was able to browse the internet. However when trying to go to
Android marketplace or login to gmail, it waits, "Signing in, need to connect with Google servers..." and then after 2 minutes says, "You dont have a network connection. .. your phone may not be provisioned
for data services. Please try again when connected to a mobile network, or connect to a WIFI network."
The solution was to go to Home, Menu, Settings and then disable the "Enable Always On Mobile Data".
Under Settings, 'Wireless and Networks' scroll to the bottom, 'Mobile Network settings' and uncheck "Enable Always On Mobile Data".
And it worked!