Bladeforce, you can use avast and trust it. You can (must) use another antispyware or antitrojan. The best (free) around seems to be a-squared, ewido and spyware terminator.
To block 'adds', you should use a good firewall or set the proper options in a good browser. Maxthon browser could block some of them. Kerio (paid version) blocks adds too.