Exactly which EMGD are you using? It sounds like you might be using the XP version on Win7 (which is allowed), however, WHQL and signing is not a feature of the XP driver set as we opted to give the driver higher flexibility and easier "on-the-fly" changability for configurability that a consumer (like notebook or desktop) driver cannot give. The issue is that to be signed, the INF has to be part of the signing and since we give YOU the ability to change the INF, then you would need to get it signed by Microsoft. The INF is the key to flexibilty but Microsoft does not like that sort of thing to change so we have to live with the difficulties with being unsigned.
I know in XP there used to be a way to turn off the "unsigned" gripping, and at one time I thought I had found similar capability in Win7 but that may not apply to WES7. The best thing to do would be to check on MSDN to see if there is a Microsoft proceedure to lighten up the signed driver policy.
Sorry I cannot help more.