You DSL modem will probably have a 10MB/s (which is WAY faster than any DSL or Cable connection might bej) output port which you could connect directly to your PC's 10/100 NIC with a regular CAT-5 patch cable.
Since you have a router/switch--it probably has a WAN port. If it does, you use (again) a regular CAT-5 (not a crossover) patch cord from the modem's ethernet port to the router's WAN port.
If you had only a hub without an upload port (usually even a hub has a switch that can switch one port to become an upload port if one isn't already dedicated to that function), would you need a crossover cable to use it.
