Sounds to me like you actually have a bit of work cut out for you then. The biggest thing is going to be making sure you get all of your DNS stuff worked out.
If you host your own DNS, this can be tricky. The best thing to do is to throw a little money at this and put a new router at that location, and bring up a small portion of the infrastructure there. After that, you can get all of the new NAT translations functional, and move the servers over to an already existing and preped network.
Make sure that the DSL line is offering you enough IP address space to accomodate all of your equipment. If you host your own DNS, make sure that you get your domain pointed at the new IP's, and then update the record on your servers. Don't forget to set up reverse DNS with your upstream provider. If someone else hosts your DNS this will be eiser, since you'll just have to point everything at the new IP's.
Expect some down time. Some people cache DNS for quite some time, so they may be looking at the old records for a while.
As far as the router, make sure you have two ethernet ports on it. If it's presently hooked up to a T1 through a external device, or an internal CSU/DSU you're not going to be able to just plug it up to the DSL modem and expect it to work, because it's not. The DSL is going to be handing off Ethernet, not a frame signal that the CSU/DSU would understand. Again, in this case I would suggest talkig to your vendor and purchasing an ethernet router that suites your needs, and getting ti all configed before the move.
You'll be much happier. I know I bounced around a lot. I hope some of this may have helped. Good luck.
