Are you talking about the ASK toolbar? If so then stay away. Most toolbars are more of a hindrance than they are worth!
My g/f and her whole family used to swear by the yahoo toolbar "because it makes things so EASY!", but once I showed them all the goofiness that it does and also set yahoo.com as their homepage, from which they can do EVERYTHING they could do with the toolbar they no longer use it.
If you want to go to ASK.com for searching then by all means feel free to, but there is never any need to download anything to use it. Anything you download is used by them somehow to make money. Whether it be collecting your browsing habits, applying pop-up ads to your system or whatever.. to me it's just not worth the hassle.
Even with Internet Explorer, you can go in and manually set ask.com as your default search provider. Still no need to download anything.