Default A4 page size in pdflatex/TeXShop combo

Hi list,

I've been unsubscribed for some time, so I hope I don't cover old 
ground here. I couldn't find the answer in the archives or FAQ, and am 
not familiar enough yet with the flow of pdflatex, dvips etc. and their 
various configuration files when using TeXShop to hope to parse the 
more general newsgroup threads.

My problem is that despite setting A4 as the default page size during 
the installation and configure of TeX with i-Installer, invoking the 
LaTeX command in TeXShop produces US Letter PDFs. I re-ran the install 
and configure scripts in i-Installer just to make sure, under a 
suggestion I saw posted elsewhere.

If I add a4paper to the documentclass at the top of my document, I get 
A4 output. I would like that to be the default so I don't have to 
remember to do for every document I create. Perhaps it would be better 
style to include that command anyway?

If it makes any difference, these three files:
/usr/local/teTeX/share/texmf.gwtex/pdftex/config/pdftex.cfg
/usr/local/teTeX/share/texmf.local/pdftex/config/pdftex.cfg
/usr/local/teTeX/share/texmf.tetex/pdftex/config/pdftex.cfg

all contain:
page_width 210 true mm
page_height 297 true mm

which sounds like A4 to me. And since I'm not entirely sure which 
applications are involved, here is the output of pdflatex --version and 
dvips --version minus the copyright information:

% dvips --version
dvips(k) 5.94a
kpathsea version 3.5.2
% pdflatex --version
pdfeTeX (Web2C 7.5.2) 3.141592-1.11b-2.1
kpathsea version 3.5.2

Of course, this is not a show stopper, since I can just provide the 
a4paper option specifically, but my oversight caused a problem with an 
assignment I submitted, so now I'm curious as to the solution.

Regards,
Heath