CCleaner is an easy to use program that is free and can enable you to clean up programs that run at startup that can potentially slow your system..

google: ccleaner and download a copy today

Reinstalling might be your best bet.. you should split the drive into 3 partitions.. i would suggest one 10GB partitions C:\ for windows to shyt on... one 15GB partition D:\for windows programs to shyt on and a third partition with the remainding space E:\ to save data to.... This way, reinstalling windows on partition C:\ does not fk about with saved data on partition E:\ for example....

I have a 350 GB HDD with 10 35GB partitions... in my system I have 10GB for windows; 62GB for windows programs; another 10GB for windows programs I might just be testing that might contain viruses; and 2 30GB partitions for downloaded and saved material... It helps!

ZoneAlarm Security Suite controls system protection, virus and adware; while AdAware is what I use to control adware primarily... this simple set of principles keeps me running sweet!!