sauron and saurman

[Leyrana Silumiel]

Saruman may have thought that he was being clever by deceiving Sauron into thinking that he was the latter's servant, but it was not so. Sauron was The Deceiver. He saw through Saruman's plans from the very beginning, and was just using the wizard to do his dirty work for him, so that he wouldn't have to expend much-needed troops, needed in the assault on Gondor.

I completely agree. To Sauron, Saruman was expendable. However, I DO think Sauron would have destroyed Saruman had he won the war. Saruman was too wise, and he would have posed at least some semblance of a threat to Sauron--greed (for knowledge and power, as with Saruman) will make even the wise do foolish things.