Loving how people are rushing to the conclusion of "durr hurr, this r good idear becuz IE lolol".
Question: How many of you still run an outdated copy of Firefox? Or Chrome? Or, hell, an outdated Windows/Mac OS? Perhaps a slightly out of date antiviral program? Would you still think this is a great idea if they were penalizing you for running those?
It's a terrible idea. It'd be far easier for them to just stop supporting IE7. They did this for the publicity, and to try to make some free coin off of people who are likely unaware of how to upgrade their network software or have the inclination to do so. I know plenty of places that use older systems for a variety of reasons, and while it's true that such systems are less secure, they're also more familiar to older users. Not everyone is young and tech-savvy and able to keep up with the rapid curve of software upgrades compared to normal products they purchase.
Bottom line: this is a dick move and I hope it ends up hurting their wallets in the long run. And it's a damn shame that people are so quick to proclaim any sort of additional tax that gets between a consumer and a product as a "good idea", as if people don't get screwed by companies enough.