How can I prevent unwanted pop-ups and self installed programs? I am using Windows 7.
The success in keeping yourself away from "harm" is to use a capable security solution. To avoid pop-ups, the best way is to have an Internet Security solution installed in your computer. From this category I can recommend using Kaspersky Internet Security, Avast Internet Security or Eset Smart Security. All these products have tools that protect you from all sorts of threats including pop-ups, spyware, malware, trojans, rootkits, etc.