I use to have Vista but the PC had cooling issues and so I was forced to by a new PC. I now have Win 7 and it isn't half bad. I kinda like it really. My advice to you is to buy Win 7 and install it. Why mess with older programs when you can just get win 7 and be done.
As far as CCleaner. You can get that for free and it cleans just fine. The one that is for purchase is a bit better but it is not sooo much better that you need to pay for it. Just my opinion if you want to save $. Have a blessed day!
