How do I manage Work Items in Excel?

I don't think you can use an Excel file containing work items on a computer that doesn't have the team foundation client. They wouldn't be able to sync or publish anyhow, so I assume you're looking for a read-only view of the data. If that is the case, you might just want to use a report off the project portal or copy the "static" data out of excel to a new speadsheet.