It is definitely not worth it if you are trying to improve your connection to the internet. Your DSL will not even stress a 10BT connect let alone a 100BT (and no were near a 1000BT). The other thing is that unless you have gigabit equipment (routers, hubs, switches, etc) you will only be getting 100BT or 10BT.
For example:
If you currently have the following setup:
Computer-----DSL Modem--------Telephone Jack
You are mostly likely use 10BT (10mb/sec [that is megaBIT not megaBYTE) because DSL modems usually only support 10BT network connections
If you have this:
Computer----\_____Router---------DSL Modem-------Telephone Jack
Computer----/
You are possibly using 100BT connection. This will not mean that your connection to the DSL modem (and therefore the internet) is faster. Not it's still poking along at 10BT. You are just able to transfer data between the two computers with 100mb speed.
So basically if you don't have any gigabit equipment now and you don't need to routinely transfer large (500MB or bigger) between multiple computers, you wont need gigabit.
