I've spent over 10 hours the last two days trying to solve the same problem. Apparently it is impossible to get rid of tooltips in Win7, which makes it absolutely unusable for me. I've wasted my time. I've wasted my money. Just installed Ubuntu which doesn't cost a penny and with one checkmark I get to disable all tooltips. With Microsoft I get to pay $100 for something that seems intentionally designed for maximum annoyance. Goodbye Microsoft. Last dime you ever got from me.
Had a laugh then thought fucking around in regedit wasn't worth it and so left it at that.
But yeah tooltips suck shit. If your GUI needs tooltips to be usable, it just needs bloody fixing. Icons just don't work when you've got more than a dozen or so choices (not much does for a human).