CCleaner is good. It only cleans up Temp files & Internet history. In fact, the same thing can pretty much be accomplshied by deleting the contents of the TEMP folder, empty the recycle bin, and deleting all cookies and history from your browser.
My advice, use it as it makes things much simpler but leave the registry alone. Even CCleaners Reg cleaner.
You can delete some entries you know 100% sure are bad entries, but the problem is theres nothing to gained (in regards to performance) from cleaning the registry.
In a sense all you're doing is taking a potential risk, no matter how sure you are, for nothing in return. So why even take the slightest chance??
As for any other tuning, the best one is Windows 7 itself. Just let it do its thing.
Defrag on a regular basis, monthly or bi-weekly. Depending on how much is added, removed changed you may not need to that often even.
And thats about all you need to do.