This FAQ explains the steps needed to install an SSL Certificate on a Windows Server 2003 OS ordered through the 1&1 Control Panel from GeoTrust. The installation is carried out via the use of a PFX file that can be generated from the 1&1 Control Panel. If you have not yet generated a PFX file, please log into your server via Remote Desktop, log into the 1&1 Control Panel and reference How do I generate the PFX file?
You may now open up a browser and navigate to https://domain.com where domain.com is the domain or subdomain that the SSL was ordered for and verify the install was successful.
If you assigned the SSL Certificate to www.your_domain.com, then make sure you add the header by following the FAQ: What is a host header?