[OS X TeX] problem using /opt/local instead of /usr/local/

[Christopher Brewster]

Systematically when I use TextMate for latex, the style files etc are  
picked up from the /opt/local/share/texmf-dist/ location instead of  
from /usr/local/texlive/2007/texmf-dist/

So I get this result:
christopher-brewsters-macbook-pro-15:~ kiffer$ kpsewhich natbib.sty
/opt/local/share/texmf-dist/tex/latex/natbib/natbib.sty

christopher-brewsters-macbook-pro-15:~ kiffer$ locate natbib.sty
/opt/local/share/texmf-dist/tex/latex/natbib/natbib.sty
/opt/local/var/macports/software/teTeX/3.0_4/opt/local/share/texmf- 
dist/tex/latex/natbib/natbib.sty
/usr/local/texlive/2007/texmf-dist/tex/latex/natbib/natbib.sty

In my system preferences, tex distribution window I have TexLive-2007  
selected.
How do I change this behaviour so as to use TexLive-2007 (or 2008 when  
I install it)?
Should I delete /opt/local/ distribution?
I think I installed it because I needed latex2rtf at some stage and  
this did not exist in TexLive-2007

My apologies if all these questions have been answered elsewhere.

Christopher

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