I can top that one (unfortunately). I wish one of my more clueless relatives had taken their computer to BB, instead of to "some guy" ... they've got an unholy (though admittedly virus-free) mess now, and I have no clue why a bunch of their files ended up in a directory named "jerry". And they won't tell me how much they spent for this, which implies that it was quite a lot.
As for the USB drive issue: viruses have to be executed. Back in the days of floppies, they could lurk in the floppy's boot block and self-execute when the floppy was automatically read when it was inserted into the computer. USB drives are somewhat better behaved (and you should have auto-execute turned off for any removable media, just on general principles). But get yourself a copy of AVG (since you've done something that attracts viruses in the first place, buying one of the fancier versions of AVG would not be a bad idea), run it, and keep it updated.