Linux-compatible server options expand

I was faced with the decision to implement an additional system on the RHEL 4.x series, or make our first jump to the version 5 releases. I decided to have this additional system to stay on RHEL 4.x because of our support situation. As admins are aware, there are many factors that affect a decision like this one.

RHEL 4.x vs. RHEL 5
RHEL is a stable platform among its competition. At just over a year old, its latest build, RHEL 5, is still new to the scene. But RHEL version5.1 was recently released and has enjoyed initial success thus far. The biggest factor in choosing to remain on the 4.x platform was Red Hat’s recent release of version 4.6, keeping the 4.x a current product. With this release, all of our versions remain within the realm of support, so our internal support requirements have not been impacted by another platform. This also keeps us in line with base configuration of applications that are running on the RHEL systems.

You can’t stay on version 4.x forever!
I know, but we made the decision based on what we can best support internally by not multiplying our scope of platforms. But, the version 5.x test bed is just around the corner, and we will increase our comfort with version 5.x (curiously awaiting a 5.2). At that point we would welcome version 5.x by ceasing the version 4.x installs, and migrating to version 5.x if possible.

What is your strategy?
Do you have multiple versions running in your enterprise? What is your thought process in regards to introducing a new distribution? Share your strategies below in a comment.