If you end up arriving on Concourse C when arriving United, I would consider taking the UA shuttle from T1 to T2, as that will cut off some walking. It is on their map:
http://www.united.com/page/article/0,,1113,00.html
I have never had to wait long, although sometimes there is a bit of a line. At worst case, I have found it to be break even in terms of time vs walking. But you get a quick interesting ride with views of the planes and you have saved a lot of walking, especially if you are arrived at the low C gates.