the speedstream 5200 is TSTT's defacto modem.
It's shitty but it works.
The old school 3com they used to roll out was the bomb but that is pretty damn hard to find now, even online.
You can buy any DSL modem that support Point to Point Protocal over ATM (PPPoA) and it would work with the TSTT hook up.
I know some guys who have Linksys models that play nice with the connection.
The specs aren't bad but they aren't great.
The games nowadays calling for real horse power, a little bit again and you will have to upgrade to keep up. The bad news is, cafe's don't make enough money to upgrade easily. It is going to be a pain, so make sure you get strong specs at the start so you won't have to be looking for extra money to upgrade anytime soon.
We are going with
1gb ram
Athlon 64 3000+
Geforce 6600GT
160GB HD
Nforce4
That should do the trick for 2-3 years.