I have read some threads already on the debate on subdomains/folder setups of sections of a website.. and if it really makes a difference or not.

I wanted to get a little more clarification on this.

I work with a marketing company that provides an array of servives. Some are connected and many are not. Ie. the sections would be,

Marketing (Marketing plans, advertising, implementation etc.)
Internet (Website design - Hosting - E-commerce)
Technology (Customized Software ... )
Retail (Retail software, loyalty programs.. CRM)
Business (business programs, data backup .. etc etc)

Basically there is alot of content for each one of these sections.. not all services are described above.

After all my investigation.. I have found a very low retention rate for incoming site viewers. Ie. Low page views.. High correlation on entry page to exit page etc. One reason I find this is happening is from the enormous amount of content someone is presented with (information overload) and they can not find what they are looking for exactly.. well this has to do more with the presentation of content and ease of navigation.

So in this case, I was wondering if segmenting the services into subdomains

ie. marketing.mysite.com would be beneficial search engine wise. Will there be any negative draw backs? Will search engines (google in particular) rank each subdomain as its own identity.. Will it weigh the site as a whole less cause it has less content.. or will it value each subdomain more for related search terms because that subdomain is much more specific. Will the linking between subdomains increase link popularity as well?

Any comments will be helpful