Approach about updating Website

Hello Everybody!

My question is following:
I need to re-build a website it was build using PHP, but now we are going to use Microsoft Technology.

I am thinking three options:
--Rebuild from Scratch using MS Sharepoint
--Rebuild using a CMS solution based on MS Technology like DotNetNuke
--Rebuild from Scratch using ASP.NET and latest release as ASP.NET 3.5 and upcoming new MVC Framework

What approach do you recommend?

Thanks in Advance for you time