werty - 9:30 am on Mar 1, 2012 (gmt 0)

Whatson, not sure what country you are in, but in the USA you can figure it is about 12-16% extra traffic.

In the US you can just signup for Adcenter, and then use their AdCenter Desktop tool, import your Adwords campaign and then repost it Adcenter and that will cover both Bing and Yahoo. Make sure you opt out of the search partners.