Dashes versus Underscores

Is using hyphens in between your keywords more effective than using underscores when naming a Web page?

Lets for Example:

Is internet-marketing.html more readable by search engines than for instance internet_marketing.html?

So the answer of this question is YES because if you have a URL like abc1_abc2, Google will only return that page if the user searches for abc1_abc2 (which almost never happens). If you have a URL like abc1-abc2, that pages can be returned for the searches abc1, abc2, and even “abc1 abc2″.

Reason behind this, please check out from here:

http://www.mattcutts.com/blog/dashes-vs-underscores/