To keep you existing environment you will have to copy the vCenter database to the new SQL Server - you can check the upgrade guide http://pubs.vmware.com/vsphere-55/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-55-upgrade-guide.pdf which does detail upgrade vCenter by moving it to a new server and database -
I had gone through the vCenter 5.5 Upgrade guide and on page 54 it says:
You cannot directly migrate an existing vCenter Server to a different machine during an upgrade to version 5.1.x or 5.5.
This means first I will have to upgrade my vCenter 4.1 to vCenter 5.0 - inplace upgrade and then from vCenter 5.0 to vCenter 5.5 to a different server.
vCenter 4.1 is already 64-bit running on Windows Server 2008 SP2.
Any other suggestions, has anyone managed to upgrade vCenter 4.1 to vCenter 5.5