I’ve heard rumours that if I use Google ad words, it helps rank my pages better in the SERPS of Google, is this true? If so would it only be for the keywords I target on ad words?

Should I be using my homepage on ad words as well as my internal pages? I.E should i be using dvd collections as a keyword for ad words?

You can go to my site http://www.dvd-collections.net if you wish to see the site.

Any help on this matter would be much appreciated.