Ccleaner is a good and free Registry Cleaner.
For Antivirus i use SuperAntiSpyware. I use to use AVG, but its too much of a hassel anymore because it has Resident Shield which is always running and even it you turn it off, when you turn it, its on, you cant totally shut down AVG without rebooting.
Here is Ccleaner
Ccleaner from FileHippo.com