Do some tests, run some tracert's, go to www.broadbandreports.com
and run their speed tests. Bandwidth is not the issue most of the time, it is the latency (lag). I have run tests when I was at a dorm connection (OC3), branch office (T3), branch of the branch office (T1), my 'rents house (fiber to the door), and I have had DSL and cable personally. In terms of playability, I have noticed that connection type and bandwidth over 256kbit affect gaming inconsequentially, unless hosting a server or a truly beefy game. During a tracert to some servers, note any packetloss or longer delays at certain hops, these will directly affect game play. Some games, this is minor and a little warping will occur, others and the game is unplayable.
I am very lucky, on DSL I was 1/2 a block to the telco, I had no lag and no packetloss. On cable, I am all alone on my node (maybe there are 2 others on it) and I recieve near full bandwidth offered. I don't go over 50ms lag until I leave the state and then I still hover near 90-100ms in the end route if it is in the US.
Oh, I am currently on cable 3.5 mbit down/1 mbit up, if I lived 5 miles east I could have 10mbit down![/edit]