If not commercially sensitive, what requests/s peak does the site currently handle?
And how do you forecast load? Do you have such a thing as a peak to average ratio? And if so, what do you use?
What do you use to monitor/analyse the logs? Presumably the weblogs from IIS are similar to Apache's, i.e. one line per request?
Do you do analysis like Mozilla do on their weblogs to see who and what browsers access the site, etc.?