How should I target my keyword expansion?

[website]

I have somewhat of a newb SEO question, but it's been stumping me the last little while, so i thought i'd try to see if some veterans could lead me in the right direction -

Scenario: My site is http://brandnamewidget.com, and it ranks #1 for "brandname widget". I want to target a related keyword "free brandname widget" --

When building backlinks for "free brandname widget", should I direct them to http://brandnamewidget.com, or http://brandnamewidget.com/free-brandname-widget ?

[edited by: Robert_Charlton at 4:52 pm (utc) on Oct 7, 2010]
[edit reason] examplified [/edit]

[aristotle]

In general you should direct the backlinks to the page that you want to rank for the term. Unless you are trying to get one page to rank high for two different terms.