Widescreen with 4:3 presentation question

I currently have a 19" TFT 4:3 monitor and considering going to a 24" or 27" widescreen. That being said most of the material I look at, MS Office documents, are for 4:3 displays. I want these to remain displayed, even on a 16:9 monitor in 4:3 format. Is this done automatically or does the OS or graphic card driver need to be manually instructed. GPU is a Nvidia 8800GTS 640mb so I'm not concerned about the card have the processing capability needed. Thanks in advance.