SHA Hash of large files in Windows I need a way of verifing the state of some VHD test environments. I am thinking I could generate SHA or MD5 hashes. 
How can you generate SHA hashes for large files, some of these VHDs are more than 10GB.
Ideally I would prefer a script solution in Powershell, Python or something wscript will run.
Thanks 

You didn't say, if you have tried any of existing tools - and if they didn't suit for some purpose. 
I would start with downloading any of a number of command-line SHA generator tools and work from there; check, eg, http://www.labtestproject.com/win/sha1sum.exe.html both for generation and checking.