Can you get an unlocked Apple iphone #g and use it for tmobile?

If you can would you be able to use the Safari and all the stuff that is on there for free or would you have to purchase a data plan from tmobile?

wi fi is free on the iphone 3g but if u want better internet connectin u need a data plan.. for ur information wi fi suck so much so i suggest buying a data paln its about 30-40 bucks a month.. u can use a unlocked apple 3g with t mobile but DONT BUY IT FROM EBAY! they will trick u instead of a 3g theye will give u a 1g that what happened to me i got a refund immediatly!