1. FC4 hasn't been updated in yrs; each Fedora only lasts about 13 mths. I wouldn't even try to put current Samba on that.
Not to mention its (FC4) security would be way out of date by now.
2. With Fedora & Redhat/Centos, a fresh install of each major version is recommended. In fact, RH officially don't support upgrades in place across major versions of RHEL ie 4.x -> 5.x
http://www.redhat.com/docs/en-US/Red...ted_Notes.html
If the machine in qn is being used 'for real' eg business, I STRONGLY suggest you get an up to date distro, and keep it updated (via net is easiest).
You could get Centos 5.4, which is a free copy of latest RHEL 5.4.
HTH