Hyperion Essbase On Windows NT/2000

We’re considering Hyperion’s Essbase running on Windows NT/2000 versus running on an AS/400. Can anyone suggest some sizing algorithm to use to size the NT/2000 box for 25 concurrent users (developers?) and 100 concurrent “viewers”. I can estimatewhatever other metrics might facilitate the process. If you’re running this product in an NT/2000 environment I’d like to know your experiences.