Recovery CD's

Most computers now do not come with recovery CD's to restore them and you have to burn them yourself. This is often overlooked by people who are setting up their new computer and now I have two friends who need their systems to be clean installed and there are no CD's to work from.

Both happen to be HP products but they are both different models. I have tried to clean them up with antivirus and antispambot programs and they both are working again but I am not 100% certain they are cleared. One of them had 25 nasty trojans and over 5000 spybots on it when I started! (teenagers with their first computer)

So, my question is:

If I burn the back up cd's from them now, will it burn clean copies of the system only or would it pick up and little nasties the cleaners may have missed and be contaminated?

Since you can only burn 1 copy I need to know if it is safe before I do this!

I checked with HP's website for ordering new discs but they are not available so burning them seems to be my only option unless they buy a new operating system (which they can't afford)