Congratulations on making this decision and starting Atkins! You are SO not going to be sorry.

The first few days up to a week (for some people) can be rough- I had a lot of cravings and it was hard to break the chocolate habit for sure- but fortunately I didn't feel really horrible (like headaches/etc) like some others do. I hope you don't either! But if you do, take heart that it won't last long and soon you'll be feeling better than you have in a long time!
If you don't have the Dr Atkins New Diet Revolution book- atkinscenter.com is a great resource. Especially the induction foods page:
http://atkinscenter.com/Archive/2001/12/15-464579.html
Stick to those induction items for atleast 2wks (recommended- some people do it longer though- I did. Depends on how much you have to lose and how fast you want to lose it) and you'll soon be through any cravings/withdrawals and feeling great and most likely have a great weightloss to show for it!
Keep us posted on how you are doing! Soon you'll have a sig line showing how much you lost also!
Oh and btw- please DO measure. I made the mistake of not measuring my first week when I lost 8lbs! So I'll never know how many inches I really lost total.

It is also a great motivator when you aren't seeing the scale move (which is usually after induction, induction almost ALWAYS shows a nice weightloss if done correctly) because seeing inches coming off is great too! Especially when it's all over so you can't really tell your clothes fitting bigger just yet.

So please please measure... like NOW, if you haven't already! You really need to know your starting point. I SO regret not measuring when I started!