Is your OS x64?
From the Installation guide:
Supported server-class operating systems
The software requires one of these supported 64-bit server-class operating systems.
• Windows Server 2008 with Service Pack 2 or later
• Windows Server 2008 R2
• Windows Server 2012
Haaa my OS is 32 bits, only 64 is?
Yes- I'm afraid only x64 is supported.
So now you have to figure out the best way to upgrade. Your upgrade choice will depend on your products and if you have things like Endpoint Encryption in use.
I'm still on 4.6.7 so I'm afraid i can't give you any suggestions re upgrade, but there is lots of information on the forums and in the documentation. Firstly i suggest you read the installation guide as it will go over the requirements for upgrading/ migrating to a new server.