One I seem to keep forgetting, but its actually very simple:
Guid MyGuid = new Guid("3c51f05f-b1b9-4ac9-af60-e9c03bfdbaa9");
And dont forget that
public Guid MyGuid { get; set; }
if(MyGuid == null)
...
will always equal false, because an “empty” Guid is actually “00000000-0000-0000-0000-000000000000″ – embarrassingly got caught searching for this for sometime once!