HELP! Migration to new Server & Upgrade SEC 4.0.x to 5.x

Hi, My Name is Hendra and I am from Indonesian, I am having problems regarding migration to a new server and upgraded.

My customers are already using Sophos Enterprise Console for 898 user since 2009, they are still using the old version (4.0.2362) and intends to be on the upgrade to the latest version v.5.1 and simultaneously move / migration to the new server.

Details for SEC 4.0 server:
- Windows Server 2003 R2 Standard Edition SP2 (32 bit)
- Intel Xeon
- 2GB of RAM
- 20GB Disk capacity
- SQL 2005 Express

Details of SEC 4.0 is installed:
The SEC does not install on drive C: \ but in Drive D: \, but it does not all installed on drive D: \, including:
- "D: \ Program Files \ Sophos \ xxx"

- "D: \ SophosUpdates" (Warehouse share folder)
- "D: \ Temp"
- "C: \ Documents and Settings \ All Users \ Application Data \ Sophos"

1. Sophos Endpoint Security & 10.0
2. Using WebCID to enable update Endpoint
3. There are two Child SUM
4. NAC Manager is enabled

New server:
- Windows Server 2008 R2 x64 Enterprise
- Intel Xeon
- 4GB of RAM
- 100GB Disk

I've followed the migration to the new server http://www.sophos.com/en-us/support/documentation/enterprise-console.aspx, but I was having problems and fail when restore the database on the new server.

Some I want to ask:

1. Is the old server needs to first upgrade to version 5.x?
2. Regarding the old SEC Server installer folder on drive D: \, is on the new server should also be installed on drive D: \?
3. Many client with an error status, such as

       - Differ policy,
       - Offline status,
       - Out of date protection
       - Auto update from server error

Any suggestions and other ways to solve it?

Thank's
Regards,

Hendra