I manage the bandwidth here at my job, and I'm constantly removing toolbars from my client's PCs. The one that pissed me off the most was the most recent Java Update -- the installer came bundled with the 'Bing' toolbar. GRRRRRR

Some of these toolbars employ 'beacons' to call home, and they're clogging up my total bandwidth here at work. Sure, at home you might not notice a few bytes floating back and forth between ZoneAlarm and you, but when you have over 100 workstations averaging 2-3 beacons, it gets to be a real drain. Stupid toolbars.
One of my sales people had so many toolbars installed that it literally took 90 seconds for IE to launch. NINETY SECONDS -- you ever count that out while waiting for something on a computer? It's an eternity. He had a full 1/3 of his screen at the top basically rendered useless b/c of the toolbars installed. There wasn't even enough real estate on the screen to load a webpage properly -- you had to scroll all the time. I removed every one of the toolbars, and his internet performance sped up tremendously. He thanked me profusely over and over. He was like, "I can SEE my webmail inbox again! I don't have scroll down just to see my messages!"
Do you really need to know what temperature it is at your house all day, or what the Red Sox score is, or the latest World news, or who's logged into Yahoo Messenger, Skype, etc etc etc etc etc etc etc etc?

Okay, I'm off my soapbox now.
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