Backing up files on a badly malware infested computer.

[compdoc]

> On badly infested computers I usually just back up the data files and
reinstall
> the OS.  

A lot depends on what you call a "badly infested" Windows machine. I'm
currently working on a Win 7 Pro machine that was infected with what
amounted to one virus, according to Microsoft's Standalone System Sweeper
tool. (It's a bootable CD) 
But the malware was a nasty one - it installed itself as the system's
antivirus, and kept popping up saying it had found many viruses, ect. And
all you needed to do to remove all the viruses was to give it a credit card
number.

 It wouldn't let me open the Task Manager, or uninstall programs, or do
anything in the way of removing it. 

But now it's gone, and with the newly installed MS Security Essentials, it
shows no infections after full scans. 

The point is, it wasn't badly infested, it was just one bad infection. And
easily repaired.