Quick Books Pro 2003, works under the new 4.2. However, I noticed that you must install everything from scratch or fresh. I run SuSe 9.2 Pro. After testing Quick Books extensively under 9.1 Pro and 9.2 Pro. I found a trick. Most people that are trying this report that when they open Quick Books it quick opens and then closes. It appears it's a DCOM95 issue and Internet Explorer.
I found that if you install Cross Over, then install DCOM98 not 95 from MS site and install. When installing it will give you an error or two. Don't fret. Then install Quick Books. It will then install Internet Explorer 5.5 and it should recognize your DCOM98 install and not install DCOM95.
Once this is installed, install Internet Explorer 6.01, then go back and install DCOM95.
Under CO 4.2 Quick Books Pro 2003 will not connect and do updates. There are some small things that are a little out of whack, but all the functions, etc all seem to work. Initially it did close out if you hit the tab key more than twice and clicking on some other things. But this was before the IE 6.01 update.