"onagar, I understood that the hackers had got control of Google employee computers, to access the Google network (but maybe I got it wrong)."
That's the story that I heard, Google machines were running IE6 and were compromised.
As to why they have them, well it might have been for compatibility testing. Or I've also heard a theory that they had to use them to access certain Chinese Government web sites to do with the censorship they were doing for them.
Which would be nicely ironic
Buda, don't worry about uninstalling it and as nighbynight says I'm not sure if you even really can. MS made a huge song and dance a few years ago about how IE was an essential and un-removable part of the Operating System and have historically made un-installing it very very tricky.
The most recent version is, I believe, meant to have an un-install but it more than likely just deletes a few files and not the whole thing roots and all.
Leave it there, just don't use it.
There is apparently going to be a critical fix for the problem released tomorrow. MS appear to have realised that this isn't the time to be using the problem to advertise newer versions of their programs and have decided to break their normal fix cycle and release something urgently.