In reply to sclly:
I would think about getting some group lessons while you're in Chamonix. I did some dry slope lessons before I went skiing for the first time (also to Chamonix) but I didn't think they were of any benefit. If I were to have my time again I would save the money and spend it on lessons in resort. The lessons last 3 hours and start at 9am, which leaves you the rest of the day to ski.
Trousers - get some softshell walking trousers (not waterproof). A zip on the lower leg of the trousers (to get them over a ski boot) is useful but not essential. I ski in these:
http://www.amazon.co.uk/Hagl%C3%B6fs-Haglofs-Lizard-Softshell-Pants/dp/B00D...
If you've already got some waterproof over trousers bring them with you (for really bad weather) but you can get away without them.
Beer - as sweenyt says, bars are expensive but you can take advantage of the happy hours. The lifts close at 4pm. If you get shitfaced the night before and don't hit the slopes until 12, you'll miss out on half the skiing.
Food is expensive on the mountain so make your own sandwiches and carry them with you. Jugs of drinking water are provided free in all the mountain restaurants in Chamonix (and France?). It's considered rude to eat your own sandwiches in the mountain restaurants but you can usually get away with it
As Blurty said, Le Tour is the best domain for beginners and Flegere has some interest as well. If you get group lessons they will arrange to meet you at the different domains within the resort each day, so where you ski for the day will be dictated by the ski school (it's probably too much hassle to change domains during the day in Chamonix).
Carrying a small rucksack while you ski is useful. You can carry a little extra clothing (in case you get too cold) and you can put clothing in it (if you get too warm). Also useful for carrying sandwiches and water.
Have fun.