Building multi-page Word docs with PHP?

Hi, I currently create my multipage docs by saving my word templates as chunks of rtf and then calling them as required as a very long string then outputting them to an rtf file and renaming it as '*.doc'. It works great except for the filesize which comes out at 900k for a two-page document. Opening in Word and saving reduces the file down dramatically, but that would prevent auto-generation and emailing - without human intervention. Does anyone know how to either create multipage docs in Word format to begin with, or to convert (on the fly) rtf to doc, or to save rtf as smaller file? MTIA George