2 Blogs on server with 1 User DB?

Hello,

I have the need to maintain 2 separate blogs on 1 server. I saw the documentation on installing a second one, but I was wondering whether the users will have to register and have profiles on each blog separately?

I would prefer to have one user DB for both blogs. The admins/contributors will be the same and we will have pretty much the same visitors on each blog, but they are slightly different topics and we want to keep the posts for the 2 blogs separate.

Any ideas? Or can you point me to some documentation?

Thanks!