I am using AnkhSVN first time. On 32Bit Visual Studio 2010 Prof it works great.

Same installation with same project on a x64 Systems does not show the green hooks nor any SVN options.

It seems that it is not installed and shows all like before. Re-Installing has the same unusable effect. No errors.
I am not sure if it is because of x64 system or not.
Any ideas how it could work?
try by changing the Source Control Provider in the Visual Studio Options
Go to Tools -> Options -> Source Control and change Current Source Control Plugin to AnkhSVN.