Virtuemart SSL checkout page configuration

I need a one page checkout in Virtuemart to be configured for ssl. A GEOTrust certificate has been installed and the website has it's own unique IP address. We do not record any credit card information, all transactions are dealt with by a 3rd party, SagePay, but we do want all other customer details recorded securely and most importantly we want the green writing indicating the page is secure visible. Currently https://ourdomain/onepagecheckout when viewed in Chrome has be red cross visible in the browser url and in Explorer the page appears as if no CSS has been detected.