Dsl would be fine for hosting a tac-ops game, I assume you mean a dsl modem since dsl is in the title of the post. I've hosted counter-strike games with dsl before, and tac-ops isn't any more resource hungry.
As to the second question, I don't understand why you wouldn't just connect the dsl modem to your PC. There's no need to connect the modem to a switch or a router and then to your PC if it's got nothing to do with a LAN, unless I misunderstand something...
