Great tips. I agree with the other moms about getting out of the house... maybe your child will let you work if you disappear into the bedroom, but my daughters wouldn't. They would come bang on the door of our office, insist Mommy do something for them, or just generally make enough noise that I couldn't concentrate on what I was doing. A few times, I ended up taking my laptop down to a local coffee shop just to get some work done. (And when you do this, be prepared to WORK. I typed 1000 words in an hour one day, just because I had a limited time to get as much done on a paper as I could. I'd also had time to think about that paper, while chasing my daughters, and just needed the time to write it.)
You'll also have to get good at multi-tasking (but hey, every mom is, isn't she?). McDonald's is a great idea (depending on the PlayPlace -- I've found some that have slides small enough for my 1-year-old) as that's a contained space where they can play. My girls like playing in our park, so if I can take a book or something to read while they are doing that, great. I just have to make sure that I keep an eye on them as well as my paper. I am also occasionally guilty of using the TV as a babysitter, though I try to limit that to about an hour a day. Maximize naptime as well.
Overall, be honest with yourself and with your husband about what you need to get done and when you need to get it done by. And work ahead, whenever possible. You might think you have lots of time to get some reading done or start a paper... start it anyway. If you have extra time, then you can relax and do something else. That's better than scrambling last minute. I also did three classes last year (without working), had two daughters at home, and NEVER pulled an all-nighter (or even stayed up past midnight) to work on assigmnents that were due. Use an agenda. Keep track of when things are due and start on them early. :)
And good luck! I'm back at school myself this year. Drop by my blog for some stories of how last year went for me (search university or student).