IIS FTP PassivePortRange
Years ago, I wrote the KB on passive port range at MSKB site -
How To Configure PassivePortRange In IIS
http://support.microsoft.com/?id=555022
Lazy to update the article for IIS 7.0 FTP detail, and I'm not going to add that here :)
Coz you can get it from Microsoft Support Team -
http://blogs.msdn.com/webtopics/archive/2008/05/14/limiting-passive-ftp-port-range-on-iis-7-0-iis-6-0-iis-5-0.aspx
One thing I recalled during testing in the past is that port range only valid from 5001 to 65535.