PR v Links v Adwords

[sji2671]

I seek to imporve in a two word search term that is not very competitive, the No1 position in G has a PR5 which I also have, however it has 174 backlinks mostly internal compared to my 31.

Should I spend money on increasing my PR or concentrate on links,asking/buying to try and do better in this search terms?

I am using adwords but out of the 1500 searches per day I am getting around 30 clicks, oh what I would give for a No1 listing in this term!

The site that currently is at No1 is an internal page as well not a homepage.

I would just like anyone's views?
Thanks
Scott