I've lost the software install CD-Rom for...

Hi,

http://h10025.www1.hp.com/ewfrf/wc/softwareCategory?product=3235678&lc=en&cc=us&dlc=en&lang=en&cc=us

This link must help you. There were number of other models I found on the same page.
Here's the page where you actually get to choose the model.

http://h10061.www1.hp.com/ccsearch/search?pname=F2100+all+in+one&qry=software&method=prodFinder&enc=UTF-8&ctry=us&lang=en&dlc=en&sni=&search=0&submit.x=0&submit.y=0

Once you click on the model you will have an option called Softwares and Downloads. This can help you download the software for the version of windows you are running in the system.

Regards,
Sai