The URLEncode method applies URL encoding rules, including escape characters, to a specified string.
Server.URLEncode( string )
The following script
<%Response.Write(Server.URLEncode("http://www.activeplus.com"))%>
Produces the output:
http%3A%2F%2Fwww%2Eactiveplus%2Ecom
See RFC2396 for more details about how to encode a URL.