Please Feedback! Unity, nHibernate, Fluent, Linq... Trying New Architecture Combinations

We're thinking about a new architecture for a set of pretty large WCF (and perhaps also REST) services that's going to be developed during the next year and perhaps you dear reader would like to comment!

The services themselves are pretty straight forward, we're going to serve data from a huge SQL Server database which unfortunately is old and lacks relationship/fk/pk between most tables. Nothing we can do about that I'm afraid but we thought that nHibernate could be a good way to map data to domain objects. Some of the services will need to handle more complex business rules, but no heavy computing or long running stuff (not atm anyway).

What more can I say... everything is going to be running on .NET 3.5, and we have a pretty good view of the business domain, we're currently modelling the information/domain together with the customer and we will probably be developing the whole thing in a DDD-ish way, using unit and integration tests, IoC...

So, currently we're thinking of WCF/REST for the service layer, Unity as container and building something around nHibernate for the Repository (looking at the IRepository implementation in Fluent). We're new to nHibernate but have been looking at nHibernate.Linq which looks really nice, and I think we'll use the Fluent API and map the classes in code instead of using XML configuration (which I'm allergic against). Just have to figure out a good way to make it all fit together, especially to get a decent UnitOfWork to work with the nHibernate session and the repository. I'll see what I come up with and post it here.

Ideas? Please comment or send me an email of you like.