I would have to agree with those that say not to worry about it too much. First, the kids get physical activity, read books (or are read to), and do other activities. It's impossible to structure enough activities in to an entire day, every day. If you want to cut a bit of that tv time out, maybe just encourage them to play by themselves and entertain themselves (legos, blocks, drawing, play doh, etc.), which should be too difficult because you've built activities in to their daily lives already.
I always said that I wouldn't let my kids watch tv; but my husband and I are in grad school, we work, and we have two young kids, so I do have to rely on tv more than I would like. I have a 3.5 year old who watches a bit of tv in the morning while we're getting breakfast, packing lunches, getting dressed, etc., then she watches while I make dinner, and sometimes while I give my one-year old a bath. Noggin is great, because it's designed for toddlers...there are no commercials, and a lot of the shows are somewhat interactive, or at least are not at all aggressive (no real conflict at all) and teach kid-values like sharing. My kids (even the one-year-old) try to help me with chores and other things, and go to bed pretty easily, and are (generally) well-behaved.
I watched too much tv growing up, probably, but my values I got from my parents. I think that's key, and you sound like a great, engaged mom who is a good role model for her kids. As they get older, I like the idea of giving them more and more responsibility around the house and for their own personal needs, and they won't have much time for tv, anyway! We'll see how that works out in my house, too. Isn't it funny how we have to adjust our parenting styles and beliefs to match our own family's needs and realities?
Good luck!