Russian Searchbar is a spyware program disguised as a toolbar browser add-on.  It was first discovered on February 1 of 2004.  It is distributed by 000 Yandex, under the company name of Russian Searchbar.  Its home page is at http://bar.yandex.ru/.
Russian Searchbar is installed by an ActiveX installer during a drive-by download.  It attempts to install itself silently, but if your Windows program is up to date, you should see a Security Warning pop up.  It tries to entice the user to approve the download by pretending to be a toolbar that blocks pop-ups, automatically fill in forms, highlight search keywords, and allow you to zoom in and out on a page.
What it really does is collect your browsing history and website information from pages you visit.  It sends this data to its server so that it can deliver targeted pop-up ads to your computer.  Your privacy may be compromised in this process.
If you have Russian Searchbar, you should remove it with SpyZooka.  SpyZooka completely cleans this threat from your computer, which other programs may not.