Al Katawazi (Author of MVC Website Programming) created a great ASPX to RAZOR converter. However, it didn't catch all scenario's. I've put some time in it to add support for more ASPX / Razor tags and the ASPX to RAZOR converter is now very usable. It's still not 100%, but it will convert most of your views without a problem. I've already converted a lot of views as a test at the current project I'm working on at Q42 and it is a real time saver.
Download the ASPX to Razor converter at CodePlex.
Are you still working in an MVC 2 project or with ASPX files?
First upgrade your MVC project to MVC 3 using the ASP.NET MVC 3 Application Upgrader
Then use the MVC ASPX to Razor View Converter