Most free programs have the possibility to either burn or mount them, again not create.
Programs that can create ISO files are often complex and/or not free.
So today I just installed a cd burner program that I haven't used for years, but its free and small (4-5 Mb). And to my pleasent surpise its have the choice to save as ISO file. Nice :-)
Hat of to CdBurnerXP http://www.cdburnerxp.se/