Do you need a data plan to browse the internet through wifi?
for example, can I go on Google or Myspace using Wifi and my wireless connection in my house without a data plan? Some people say yes and otehr say No. What is the answer? I have AT&T. Thanks in advance to everyone!

Yes if you switch the browser config to WiFi or HotSpot browser.

Honestly it depends on your provider. I work for T-Mobile and if your wifi is on you can browse all you want without a data plan. What I would advise you to do is contact your provider for clarification.

I heard that wifi isnt possible for surfing on the Rogers Branded units, anyone know forsure?

If you go to Options >Advanced Options >Browser and make Hotspot (Wifi) Browser the default browser, then you can surf even without a sim card. I've done this many times with 8320's. You can't get any email or send pin messages, etc. But you most certainly can use it for surfing the internet.