The case number pretty much determines when your interview will be. It starts with 1 for each region... Since not everyone who receives the notification letter decides to apply for a green card and since not everyone who gets an interview receives the green card (because of background check or not enough funds, etc.) no one should give up hope. In the visa bulletin it says that for DV-2007 all numbers in all regions are current, so everyone who received the notification letter (and sent in the forms) should get an interview.
About how to read the visa bulletin: Check the numbers in the diversity immigrant (dv) section. If your case number is below the number listed for your region, your number is current in that month (but this doesn't necessarily mean that your interview is exactly in that month, it might be 1 or 2 months later (at least this is what I learned from this forum)).
The interviews for DV2008 will start in October. The information about the current numbers in October will be in the September visa bulletin (the bulletin includes advance notification for the following month) which will be published around August 15th.
I hope this information helps. I'm also new to this (I'm a DV2008 winner as well)... if you search in this forum you can find answers to most of your questions.
Good luck!