You should just disable the preview pane then. If it is a virus, you're likely to get infected by just previewing it, and not even "double clicking" and opening the email.
If you have preview disabled, you can right click, select properties, and usually gather enough information as to whether you want to open a suspect email or not.
If you don't, as soon as the message is highlighted, it's opened, per say, and alot of the newer worms can infect your system at this point. Why take the risk?