I found a new article at searchenginewatch about a study made between non-branded and branded search terms.

These findings have significance for several reasons. Supporting the findings of other studies of searcher behavior, searchers tend to click generic, non-brand terms earlier in the search process, and more on brand terms when they are closer to making a purchase. This suggests that search marketers can leverage non-brand search terms to drive searchers toward brand terms later in the searching and purchase consideration process.

Based on this study, a typical search behaviour goes like this.

1. people search for "golf clubs"
2. then they find a nice brand and search for "callaway golf clubs"
3. they find an interesting putter called callaway i-trax
4. they search for "discount callaway i-trax"
5. they buy

As an internet retailer, what does this tell you? It is best to concentrate your efforts at ranking for "discount callaway i-trax" or variations of it such as "cheap callaway i-trax". If you end up on the first page on search terms used by buyers near the end of their research process, then there is a high probability that they will buy from your store.