Do outbound links increase SERP rankings? Will NOFOLLOW decrease them?

outbound links google serp rankings nofollow

[MikeSchinkel]

I have two related questions so I am going to post them as two seperate questions in two different forums. Both involve an advertiser requesting that I change my site.

First, let me describe my site. We publish "guides" in print, PDF, and HTML format that help people select components and tools for .NET/ASP.NET development. We've published four guides to date with another nine scheduled and then a lot more planned after that. The site is relatively new but we've already got PR5 for two of the four guides including the one the advertiser is questioning (PR4 for the other two and PR5 for the home page.)

Currently the HTML for each guide is all on one page (though I plan to slice them up into lots of little pages) and the HTML page includes outbound links to the vendors and products covered in the guide.

Here is one of the two questions: Do outbound links to quality pages that have content that supports the main message of my page help my SERP results or have no affect? For example, if I have a page on my website about engine modications for a Ford truck and my page linked to links of products for hopping up a Ford truck, would that help, hurt, or make no difference in my results?

Also, would adding rel="nofollow" to some of my links (as one of my advertisers is asking) help, hurt, or have no affect on my SERP rankings? (Please ignore the issue about the advertiser asking for this; that was my other question in another post in another forum.)

Thanks in advance for any thoughts on the matter.