Do SE's devalue the quality of many links from one site?

[DXL]

Let's say I own a 300+ page (.html) informational site related to a particular sport, PR3-PR5 for every single page and plenty of unique quality content. Then let's say I own another site (on another server) for a business that sells one product only, which is related to that exact same sport.

If I make the generic product name the anchor text, and then place that link on all 300 pages (near the sites text menu at the bottom, or a text menu called up by an include), does that mean that I've gained 300 quality backlinks just as strong as 1 link each from 300 different websites? Or do the search engines devalue the quality of multiple links if they come from the same site?

[seolole]

They will disregard most of your links.
How much links will it exactly be worth?
I would say it depends on the search engine. In my opinion, Yahoo or MSN value those links much more than Google.

[DXL]

If google will disregard the links, does it mean that its not even worth having a link on every single page pointed at the other site, then?

So basically, 1 link from 10 different websites is stronger than 20 links spread out on just one site?

[Robert Charlton]

If I make the generic product name the anchor text, and then place that link on all 300 pages (near the sites text menu at the bottom, or a text menu called up by an include), does that mean that I've gained 300 quality backlinks just as strong as 1 link each from 300 different websites? Or do the search engines devalue the quality of multiple links if they come from the same site?

I could even make an argument that the engines might count all 300 links less than they might count just one.

That's because 300 links certainly suggest a less than arm's length relationship between the two sites, perhaps making the engines think the links might bought or otherwise commercially motivated.

This is conjecture. I always try to avoid having many links from a site.

[DXL]

As far as multiple links from just one or two sites go, I do know that it at least affects pagerank. I had a site that sold widgets, on two different 300+ page PR5 sites that were totally unrelated, I had a link to the widget site. In under a year, the widget site became PR6 and has stayed there (I've sinced removed the text links). It also pushed the site up in the SERPs. So maybe the links don't carry as much weight, but it definitely must count for something.