rundll32.exe url.dll,FileProtocolHandler http://www.jsiinc.com

OR
rundll32.exe url.dll,FileProtocolHandler http://www.jsiinc.com/reghack.ht%6D

OR
start www.jsiinc.com

OR
start www.jsiinc.com/reghack.htm

NOTE: Rundll32 doesn't like .htm or .html files, which is why .ht%6D works, %6D is the hexidecimal code for m.

NOTE: The above commands will use an existing browser window if one exists.

To always open a new browser window:

"C:\Program Files\Internet Explorer\IEXPLORE.EXE" www.jsiinc.com

OR
"C:\Program Files\Internet Explorer\IEXPLORE.EXE" www.jsiinc.com/reghack.htm

To open the browser window at a fixed location and size:

"C:\Program Files\Internet Explorer\IEXPLORE.EXE" javascript:window.resizeTo(1194,960);window.moveTo(80,5);location.href="http://www.jsiinc.com/reghack.htm" NOTE: rundll32.exe url.dll,FileProtocolHandler www.jsiinc.com also works.