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. 1 line per request?
Do you do analysis like Mozilla do on their weblogs to see who and what browsers access the site etc?