Passing Objects between Applications

Hello everyone. I'm very new here (this is my first post) so I apologize in advance if this question has been asked before. I've done some research already, but I don't think I have found the right answer yet.

Ok..here's the set up.

VB.NET 2008 CE 3.5  Framework.

What we want to do is to have multiple applications using the same basic object information with the ability to pass the object's property values from one Application to another.

For example, the first application to run is a logon process that creates the object: obj_User with properties like User_Name and User_ID and so on.

This object information, (no methods required, just the property values) needs to be sent into another Application that is executed from the logon Application.

Our thought was to have a background service running that holds the object's information and the next Application can reference that object's information.

So, what is the best approach here? Interfaces, Reflection, Serialization, WCF? I'm familiar with the concept of an Interface but I have not worked with one directly.

Any discussion and help on this would be greatly appreciated and I again apologize if this topic has been covered before.

Thanks....