You say you "have made some changes on my main page (new keywords and content changes reflecting new keywords) ", but did you optimize your site by doing direct comparisons with other websites who are getting top 10 rankings on the same keywords as your site?
Unless your site is optimized for Google and MSN, do not expect to get an increase in traffic.
I am trying out the IBP-9 Search Engine Optimizer. They offer a free trial version, but to really optimize your site, you have to buy the full version.
-- This message may have been cut off and the rest will only be shown to members. To become a member, click here --