This question seems to be getting repeatedly being asked without any clear answer.
So here's my angle.
W2K3 will cost you money and GUI resources !
Fedora is unsupported, bleeding edge and only intended for "non-critical computing environments"
http://www.redhat.com/en_us/USA/rhel/migrate/whichlinux/
well all my VMware Player & Server deployments are "critical" to me PLUS give those hardworking developers at VMware a break and let them focus on enterprise level supported solutions
So in my view its a simple choice between Red Hat Enterprise 3 or 4 or CentOS 3 or 4 since BOTH are 100% GPL free software systems which you run on as many systems as you like.
\[Be aware that the RHN subscription IS chargeable and separate from the RHEL system and that under RHN terms you need to buy RHN for every physical AND virtual system you deploy across your entire organization. If have already signed and you disagree with these terms you would need to contact Red Hat to make arrangements to terminate it]
So what do I actually use at the moment ?
CentOS 3 host (without X-Windows) with CentOS 4 guests (with X-Windows)