Automate Blackberry SW Version Update.

I know that by using the following code in an asp page
<%Var1 = Request.ServerVariables("HTTP_USER_AGENT") %>
It will return the following: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0) BlackBerry8703e/4.1.0.377Profile: MIDP-2.0Configuration: CLDC-1.1*******

What I need to capture is “BlackBerry8703e/4.1.0.377” and check to see if it equals “BlackBerry8703e/v4.2.1.110” or other version number. If it does not, have them redirected to a page that will instruct them how to download and install the proper SW version.

Can anyone help me out with this?