all you need is vs2010 and a browser.
what do we need a browser? hehe,if you want you vs2010 support html5. first thing first is that you need update vs2010 to sp1.
How do we up microsoft Visual Studio 2010 to microsoft Visual Studio 2010 sp1?
There are two ways:
1.Go straight to microsoft website, download center download Microsoft Visual Studio 2010 Service Pack 1
2.open windows update, the system will automatically find vs2010 update file, size around 600MB
Once you finished update, then open you vs2010 goto tool->option->HTML->Validation