I'm planning to change one server Microsoft SBS 2003 with SharePoint, Exchange and SQL database into something that will provide me with some redundancy and won't be single point of failure.

I was thinking to buy 2x exactly the same physical servers and put 2 virtualized servers on HyperV or VMWare on each.

Then i would put SharePoint, Exchange and SQL on that 1 physical server (shared onto 2x VM's).

I would like 2nd physical server to be exact duplicate of the first one so that when 1st server goes down (for reboot or hw failure), 2nd takes care of everything so that users don't even see anything changed (in terms all their emails, sharepoint stuff is available).

My questions are:

1. Will I have to pay for licenses for both servers even thou only one instance of SharePoint, Exchange, SQL will be used at same time?
2. What are proposed solutions to do that? Any additional hardware I would need, any complicated software configuration to be expected to configure such redundancy so that when one physical server goes down 2nd one is taking care of rest?
3. What problems should I expect?

This solution is for 60 people. Later on it may or may expand.