Question about upgrade paths

What I'm using now:
Redhat 9.0

What I've used in the path:
Redhat since release 4

What I use my current implementation for:
[list=1][*]Apache web server 2.0.49[*]PostgreSQL 7.4.3[*]PHP 4.3.7 (pre-5) work[*]Customized applications using various ports[/list=1]

The new machine I'm building will have dual-procs (AMD Opteron 220 series) and 4gb of DDR400 RAM with RAID 0+1 SATA 120gb drives. Since RH has stopped support for their current versions (9 and prior) as of April 30th, I'm now in the market for looking around. Some of the customized applications say they "require" RH ES (enterprise), but I've had no problems with them on 9 so I can't imagine they're using the ES-only kernel modifications.

All that said, what do you guys recommend? The server is up 24x7 on a business-class RoadRunner account (2nd tier, 4mbs down, 1mbs up) and the web service is the most used as I run a message board (PHPBB 2.0.8a) and that requires both PHP and PostgreSQL so you can tell where the priorities lie. I don't plan on doing any SMTP unless I just decide to, but I doubt it, so that's one less consideration.

All this is hooked into the internal network that's split by the Linksys 8-port router I have and I'm looking to get back into a single DLink router and jump off it with an 8-port gigabit DLink switch so that the internal network will be screaming (as much as I can make it so with optimizations on standard home equipment).

GOAL:
I'm looking for a very solid linux-based operating system that supports small-medium business levels and the kernel is either 2.6 or 2.4 tweaked with various modifications/optimizations, etc. I'm not worried about paying good money for a good product and while I'll get a standard year of support with any purchase, I'm not worried about that considering I've been managing my own for quite a while, hehe.

So, bring on the ideas! I've done some looking but I've never delved into the whole "buy an enterprise OS" so I figured I'd ask. There are bound to be a lot more professional people out there than me, hehe... :D

Hi, what problems are you trying to solve with an upgrade?

You can stay with RH9 and use the legacy upgrades to stay current.
http://www.fedoralegacy.org/

RHES is great if you want to go commercial.
Why not just go with what you know.

In my office we have Solaris, Linux and Irix
The community support for Linux blows away Solaris and Irix
So I like it better. Answers for Linux issues are almost instant these days.

Good luck with your update!!