Need software recommendation plz!?

I'm looking for a completely free way to clean up my PC of spyware/malware/and viruses. I already have AVG, Malwarebytes, CCleaner, and an additional registry cleaner; however, my darn computer still seems to be bogged by something and I am wondering if there is another option out there that will scan and clean without asking for any kind of purchase. Also open to any other suggestions that help to speed up performance. I have Windows Vista. Thanks in advance for your help!