It took me longer to find this than I expected so I'll post it here.
I've frequently been harping on SQL Server Express (SSE) as a replacement for Access and any kind of local persistent data caching or storage. Here's how you open a local database mdf file. In addition SSE can create an instance for you where the server is called a User Instances. So pick your poison. I'll have to play with it to figure out mine. If you've been playing with it for a while, what do you recommend?