This did take some time to think about, but it’s pretty easy.
1. Kick off a workflow when the item is created/modified
2. Add a delay in the workflow. This is because if the look up into the list is done too soon, the item saved sometimes, can not be found.
3. Perform a look up on the Item id and compare.
Ever had a situation where the document opens in Read mode, instead of getting prompted?
This is a known issue with Office 2003 and MOSS 2007, the easiest way to fix this is to install any Office 2007 component / to modify the registry keys as outlined in this MS KB article: