Use Microsoft Security Essentials as an antivirus/antispyware

it's very good and fast.
Clean your system with WinOptimizer/TuneUpUtilities or some other crappy software, it doesn't matter - they all suck. use ccleaner afterwards (this one doesn't suck).
If you don't have a SSD, defrag your disk after you cleaned all the shit up. Use O&O Defrag, it's the only one that does the job done.
P.S.: McAfee, Norton, DrWeb, Kaspersky and other software that have the names of 'human beings' tend to suck.