Seosoftware homebuild/buy/opensource

first of al sorry for the bad english..

We are planning to do more Seo for our customers, so we are looking for software that could automate the proces.

We are currently making a list of interresting keywords and to compare them we have a xlsfile with the number of searches (overture) the number of results in google and a direct link to suggestions on that word. then when we have a suitable advice we make pages with the costumers homesite layout and content that is related to the keyword to get the right density. if we have ten keywords to optimize we make ten pages.

Is there a system we can buy or better: open source (php) what suits to our way of work? opensource(php) would be the best because we could program the things we are missing.

for example : A script php script that could query overture and google to generate a overview.