[Apokalipse]

reformatting means erasing all contents of the hard drive. i'd say it's likely because he wants the cotnent he looked up to be removed...

[Apokalipse]

by formatting, you aren't putting on software. you are erasing all of it.
but he will have to reinstall Windows, hardware drivers and any other programs you might use.

If he wanted to put on software so you cannot detect it, he will be able to do so without first formatting it

[DJ-CHRIS]

Naah if he wanted he could just install some stuff + a rootkit right now.

Infact, he most likely already has them on.