Is Windows 7 reinstall still effective agains virus threats

I am asking because reinstalling Windows XP meant formating disk and installing a clean genuine copy of the system.
With Windows 7 all files on disk remain and only the kernel of the system is reinstalled. Is that even safe?
If all files are left exactly where they were that means all viruses and mall-ware can remain in the system as well.
Answer #1
Yes you can format your harddisk and install a clean copy of windows 7 just as windows XP
Answer #2
Answer #3
Just do a clean installation and you should have no viruses, but if you did an upgrade then yes it is possible to have viruses, since programs and data are still there.
Answer #4
RandomNooob replied: Just do a clean installation and you should have no viruses, but if you did an upgrade then yes it is possible to have viruses, since programs and data are still there.
I am not sure… I follow the standard Windows 7 installation procedure and every time the files remain (which is a good thing because one often forgets to make backups of something and its gone)
I mean it has never happened that after reinstall there have remained any viruses the system has always been clean and quick afterwards however I am just curious.
Answer #5
when you are doing a clean installation
you choose advanced.
then it would show you your drives,
just click on that and click format.
then the go next and itll install.
note this time your files won’t be saved.
Answer #6
boot from the windows CD and delete/format the data off via the CD.
Answer #7
I see… thanks for help