e2k3 upgrade to e2k7



I've got e2k3 SP2 cluster in w2k domain and forest and will be upgrading to
e2k7.

Can you please advise whether the new e2k7 server should be running w2k3 or
w2k8 - my manager is not keen on using w2k8 before sp1.
In your experience will you discourage us from running e2k7 on w2k8 so
"soon"!?
.