First, what problems (if any) are you having with CentOS-4.3 other then you think the applications are old???? If you want newer applications some are easy and some are a bit harder to install into CentOS-4.3, do you have any in mind you really need/want????
For example (just downloaded/installed from
http://www.openoffice.org/ );
$ rpm -qa --queryformat="%{n}-%{v}-%{r}.%{arch}.rpm\n" 'openoffice*'
openoffice.org-core03-2.0.2-5.i586.rpm
openoffice.org-core10-2.0.2-5.i586.rpm
openoffice.org-spellcheck-2.0.2-5.i586.rpm
openoffice.org-core08-2.0.2-5.i586.rpm
<snip, you get the idea>
In answer your question, I perfer to keep the unoffical repos really small just dags repo. But at the same time I'm used to downloading and building rpms if needed from the source when I desire a newer application.