How can I block itunes from using vpn connection

How can I block itunes from using vpn connection?

Im playing streaming radio via Itunes and have VPN connection to work

Work internet is slow and I want to use my local ISP for the itunes radio.

I have to enable use remote default gateway on my vpn connection thus itunes is streaming via work's data pipe

I tried using windows 7 firewall with outbound rule and specified the VPN subnet

I don't think its working

any suggestions?