Software Deployment

I'm looking for some best practices or recomendations about deploying applications to 64 bit machines in a mixed environment.

To give you a bit more background, I feel confident repackaging applications using adminstudio and I use group policy to deploy these applications. My Organisational units are separated by department and my policies to deploy the software are applied at this level.

In the future some departments will benefit from having 64bit operating systems and applications. However I don't want to change a whole department in one go. I could serpeate each department into two groups, 32bit and 64bit, but I would rather avoid this.

In the past I have had organisational units with mixed 2000 and XP machines. This caused problems with certain applications where I required two packages to deploy to each operating system. What I did was set the XP pack to upgrade the 2000 package. It's ugly and meant that the upgrade package would try (and fail) to install on the 2000 machines. There must surely be a better way than this.

I'd like to be able to manage software policy on a department using one policy but I might have to accept it and subdivide each department.

Has anyone got any suggestions or general background information on what the recommended way of dealing with the potential deployment of 64bit applications to a 32bit operating system.

Cheers