Is description during submission effects ranking?

[sumit4322]

Hi,
I've submitted the my site in the several directories & SE.

Are the title & description given importance by the search engines like google, yahoo? Should the description must contain the keywords for which one wants to get good rank?

If yes, then I wanna know, if I would start targetting the new BUT related keywords for the same site, then is it compulsary to change the descriptions on search engine directories?

Becoz I've already done required SEO work(meta tags, body content etc) and still not getting good rank on the desired keywords.

[sumit4322]

There is nobody to reply my little query.

:(