If you want to fix your Google search to a specific Google location, I recommend that you download and install the free plug-in Glims:
which not only does that but much more equally useful stuff! Such as enabling Safari to run full-screen, and more.)
(It adds items to Safari Preferences).
Not only does it already list a number of search engines and regions, but you can also add any other search engine not already listed in Glims by using the method described here:
Just enter the name you give the search engine in the name field, and the URL for it in the Query URL field.