A search with Google using "monte carlo" and "excel" as
keywords should yield plenty of commercially-available
software packages, many of which are just Excel add-ins.
Also check out:

http://www.vertex42.com/ExcelArticles/mc/
http://www.usfca.edu/fac-staff/middleton/risksim.pdf

HTH
Jason
Atlanta, GA

-----Original Message-----
I am looking for a software package that can be used for
monte carlo
simulations on investments that integrates with excel
(e.g., at least for
uploading data and downloading results). Any
suggestions?
.