I don't have pics of the old vanity.. we haven't purchased the new stuff at all yet (we're going to Lowes this weekend to stock up on some stuff).
I think the sink is separate from the cabinet, but purchased in the same "kit" - can't tell from online descriptions. I think it's the same size cabinet because it's almost the smallest out there... here is an example of something *like* what I want to buy:
http://www.lowes.com/lowes/lkn?action=productDetail&productId=132135-444-C14024A&lpage=none
The current cabinet looks the same, a little counter space (if you can call it that) on either side of the sink and two small doors in front.
We're actually probably replacing the drywall where the medicine cabinet is going up, we pulled this old thing off:

There are some wires but we can't tell if they go down or across (across would bring them around the corner to the switches they used). So we may be able to leave that section un-drywalled. The one I had in mind is this:
http://www.lowes.com/lowes/lkn?action=productDetail&productId=23881-336-X4311&lpage=none
It appears to be sized to fit between the studs, 14" W.