I have the "Tech Support" one on our office wall :) As much as I'd like to do the same for the last one, we often have to remind ourselves it's our job. To help people that is, rather than visualise the virtual murder of some people.
Doesn't mean it doesn't happen of course... :D These days though, it's more often virutal suicide! ;)
I've seen #3 before, and it's the most recognisable for the job. But that said, I'm probably #1 now :( (holding a big rock that's about to come crashing down on me...)
Another one im sure we can relate to!
How computers are made