Cat5 is better. Thermostat wire doesn't have the twists that are necessary to cancel interference from stray electromagnetic fields.
Gary VanderMolen --------------------------------------------------
That reminds me, I did the same as well. I ran 6 lead thermostat copper wire for my phone line, a dedicated run from my jack I was using for the DSL modem to the NID. Figured it couldn't hurt. Used to always do that from the days of the 2800 modem and POTS lines.