Guidance on migrating a .NET windows forms application to a web application

Question

Are there any good books or websites on this subject covering subjects like:

• different migration scenario's (big bang, module for module, function for function) pros and cons
• do's en dont's
• tooling
• handling customer expectations

We have a rather large winforms based product which we would like to migrate to the web. Migrating in a 'big bang' scenario would probably take at least two years. We're looking for alternative scenario's. I'm especially looking for ways to handle the inbetween scenario, what options do you have to keep customers happy.

• Let them use the windows application at the same time as the new web application?
• Let the windows application use the new features from the web application via a service interface?
• Accept the cost of double maitenance for a while to keep customers happy?