Description wont make a difference, title may.
Particularly in MSN and and SE that relies quite heavily on on-page optimisation.
Thinking about it again though, Im really unsure if title changes will hurt your rankings.. actually I cant see how it could, as long as the keywords your ranking for are still in there.

These days a meta description tag that is not "unique enough" can sometimes cause Google to tag the url as an Omitted Result or even a Supplemental Result. It's not clear to me if there is any other impact (going higher or lower) on Google ranking or not right now, but in recent months the meta description can be like an off/on switch for showing up or not showing at all.

thanks a lot..
wel my site has just got only its home page indexed..and its not showing up in the first 3 pages in google on the keywords i wanted it to.. so i changed rather twisted the title a bit givin prominence to the keyword i wan the site to come up on...so will it help me to come up in the serps?

...so i changed rather twisted the title a bit givin prominence to the keyword i wan the site to come up on...so will it help me to come up in the serps?

seo5 - There are a huge number of factors that affect rankings. The title is one of the most important onpage factors when it's supported by html text content on the page. So yes, adding your target terms to the title should generally be helpful if you fit those conditions.

That said, maybe your page isn't really strong enough to rank in the first three pages of Google for other reasons. Inbound links are a big factor with Google. Age is another. It sounds like your site is new. It may well take you nine months to a year to rank on anything competitive.

If "keyword" means one word, and that word is competitive, it could take you many years and a lot of good quality, relevant, inbound links with the right anchor text.

thanks..
yes my site is new and got crawled just two days back..i have been working on links and dir submissions..wel i changed the title but it still aint reflecting in the page indexed by google..till when can i expect to see it gets crawled again and update the changes..i mean how much time wld it take approximately....