Scanning One Computer Using Another

Hi All,
I use Windows 7, and like most folks, have used other operating systems in the past.

I would like to know what computer equipment and software (ideally freeware) I need to connect to another computer to see what is in their hard-drive.

This may mean my seeing the other computer from my own computer as an external drive.
The more important thing I want to know is how to connect to another computer and be able to scan it for viruses using my own anti-virus in an example of the other computer being infected or not working to optimum levels like a service of denial attact forcing somebody to constantly force shut down their pc.

My question above relate to both connecting and scanning of same and differing operating systems like Windows 7 to Windows Vista or Windows Vista to WinXP.

 

I just hook up the offending drive to my computer as a slave. Or use a USB adapter. You might look into possible problems using an older OS to scan the disk of a newer OS, but I don't think there would be a problem.

If you are talking about doing it via network, please ignore my post.:cool