First of all, nothing has changed - in theory - on the computer-to-router side of things, so the default gateway address should be the same as it was before. You mentioned 192.168.1.1 - are you certain that's what it was?
If you go to Network Settings then double click the relevant network icon, then choose Support, the gateway address is there.
As far as getting connected is concerned, you've got no chance until that MAC address is sorted out.
On the router, is the DSL light on and is it steady or blinking?
I don't know anything about Talk-Talk - other than a lot of our customers have had problems with them - but I can only see their disk supporting their router equipment. I can't see how running this is going to help set up this router unless you got very lucky and it is the same model that Talk-Talk supply.
To me, routers are set up in three stages.
1. Connection between router and line (DSL light?)
2. Connection between PC and router (and I don't mean just detecting it, but connecting to the default gateway)
3. Using the PC to tell the router to let people access the Internet as necessary (so entering account details and - if they're messed up - changing IP ranges)