100BT and 10BT is 100 meters max, you will not have an issue unless you make your own cable. Very few get the wiring pairs correct.
I want to increase the distance either between (1) my DSL modem and my router; or (2) the router and my desktop computer. Both obviously are connected with Ethernet cable. I want about 100 ft. Does it matter if either of the above are separated by that long a cable?