If you get DSL and have the ability to do so confidently, I highly recommend setting up your internal wiring structure as follows. This requires that you have access to the wiring at the service entrance to the house - you will need to splice the primary feed before it hits the mult-box. Additionally, you will need to be able to run Cat-5 to your office area.
I apologize for the crudeness of the diagram.
<img src="http://i2.photobucket.com/albums/y12/e647g9i/DSL.png"</img><br>
In a nutshell, you are applying one filter to the entire phone branch. You won't need to have any filters on your phones. I keep the DSL modem near the service entrance to reduce wiring, and have a small UPS devoted to that DSL modem. Then, Cat-5 is run to the office area, which feeds the router. After I did this, stability of the DSL connection greatly improved.
Another idea comes to mind. Let's say you have a mult-box near the service entrance, and you know the Cat-3 run to your office area is dedicated, and therefore runs directly to your mult-box. Also, let's say you are only using one pair (red and green wires) feeding one phone line to your office area. You could use the second pair (yellow and black) as your DSL unfiltered feed. It might look something like this:
<img src="http://i2.photobucket.com/albums/y12/e647g9i/DSL2.png"></img>
If you have any connectivity issues with your DSL service, it's worth a shot as the materials and effort required are negligible. Again, by doing it this way, you won't need to use any unsightly filters on your phones - and more importantly, you won't have to worry about someone plugging in a phone to an unused jack that is unfiltered.
edit: Another comment - if you have an unused row on your mult-box, you can make the operation nice and tidy: remove the input of the row that corresponds to the DSL line, and attach that to a new row. Hook the yellow/black wires of the new DSL office feed to the first mult connection on that row. Now, connect another pair to that same mult connection in the second position, and hook that to the input of the filter, and hook the output of the filter back to the input of the original row. It's the same thing as in the diagram, but done cleanly.
<img src="http://i2.photobucket.com/albums/y12/e647g9i/DSL3.png"></img>