I have following questions.
- Is it possible for spyware or any other software to install without user initiation and notification ?
- I have dual boot(windows 7 and 8), is it possible that any spyware(or virus) in one OS also works in another OS too ?
Q1: Certainly. In fact it is now very common. A common vector now is from rogue adverts on web pages exploiting vulnerabilities in the browser or in Flash/Java plugins.
Even when malware is not cross platform, it is still possible for it to travel across OS's by changing files.
1.Spyware is designed to spy in stealth that's why it's known as a spyware. It won't inform you that it's there. 2.All spyware is backward compatible so if it will work in win32 and Win64 Windows7 and it will also work on Win8