Many people are considering their options when it comes to moving/migrating Enterprise Vault from their existing hardware to 64 bit - usually to Windows 2008 R2 x64, as a preparatory step of going to Enterprise Vault 10.x

There are several ways to get there.

I certainly wouldn't recommend any kind of Operating System in place upgrade.  It just always seems to end in unhappiness.

I would suggest one of these ways:

First Way

Use the Enterprise Vault Server Settings Migration wizard.  It is described in detail, and available for download:

http://www.symantec.com/docs/HOWTO42445

I personally have not yet used that.

Second Way

Use the Migrating EV 9 to 64 bit documentation available here:

http://www.symantec.com/docs/TECH141481

I have used that a couple of times lately, and it's worked very well.