Just to revisit this topic..
I tired another time to get a definitive answer on whether a Headband of Vast Intelligence grants *only* specific ranks in a knowledge skill; or if they grant specific knowledge ranks in addition to skill points for having an increased intelligence.
I didn't get an immediate answer, but I got a poster who said that it had been answered before. Paizo's search engine is pretty crummy, so I tried googling to look for old Paizo posts.
I came up with a remark from Jason Bulmahn back on July 13, 2008 specifically regarding the Headbands. Note.. it would not come up for me as I think they deleted the forum it was in, but I pulled it up by trying Google's cached page instead.
http://paizo.com/paizo/messageboards...lPoints&page=1
"Hey there all,
You might also note that Headbands that grant and Int bonus should now include what skills those bonus ranks are put into. This is to clear up the confusion and prevent the headband from becoming interchangable skill ranks.
Jason Bulmahn
Lead Designer
Paizo Publishing"
And other sources have indicated he's stated this also in a set of instructions given to GenCon GMs who had rule questions.
I have found someone else quoting him saying that a permanent increase of Intelligence, though say a wish spell or a book, would grant retroactive skill points.
I believe the language on Page 555 about Permanent Stat increases comes across as wishy washy to me is that he's addressing several scenarios with one paragraph. A stat increasing item is one way to get an increase in an ability.. but there is also wish spells and Tomes. The paragraph on Page 555 address both scenarios. The language specific to the Headband of Vast Intelligence stats that their bonus ranks are hardwired into a specific knowledge skill is to prevent that method of increasing your intelligence to be an exploit in continually redefining your skills every time you take it off and put it back on for 24 hours.
So.. I think the Headbands give you specific knowledge ranks, and you do not get any extra skill points. Those specific knowledge ranks are what you get instead extra skill points.