If you are trying to compile RRDTool (at the time of writing, 1.4.5) on CentOS 5.x, you will need install the following packages on yum:

yum install cairo-devel libxml2-devel pango-devel pango libpng-devel freetype freetype-devel libart_lgpl-devel

Then, just compile rrdtool as usual:

wget http://oss.oetiker.ch/rrdtool/pub/rrdtool-1.4.5.tar.gz
tar -xzf rrdtool-1.4.5.tar.gz
cd rrdtool*
./configure --prefix=/opt/rrdtool
make
make install