G'Day Dan,
I'm not saying that 2.2.19 is not a supported Red Hat kernel. However, as I've said before on similar topics, it's not 'standard' as 'standard' goes simply because if it was, RedHat should have a distro that is available for download (RH 7.0.1 ? or RH 7.1.1 ??) that uses 2.2.19 out of the box. Then, and only then, will we see vendors / manufacturers even make an attempt to support different kernels of a particular RH version.
I can see the manufacturer's point of view as far as kernel support goes. Unless it is mainstream (ie. Generally available - especially to less sophisticated users who rely on the "out-of-box" experience and simplicity - forget about kernel patches, upgrades, blah, blah.... that's not a realistic expectation of end-users), they have really very little incentive to support it. I mean, there will always be someone wanting support for kernel 2.2.19 then 2.2.20 just because it does something the other does not (even if it breaks something else) , then 2.2.21 ..... where will it end ? Much as we love to hate Windows, this problem is not as severe in the Windows world (yes, it can still happen .. Win98 drivers that don't work 100% in Win98SE but it's not often).
The actual solution would be for the manufacturer to support the Linux cause by releasing driver sources so that we can "make our own to suit" as was recently done by Highpoint (THANK YOU Highpoint !). However, not many are quite so willing (even Highpoint took some grovelling). Until that happens, Linux users who know enough to tinker with it will ALWAYS have this problem. Those who don't know quite enough usually tend to stick to "normal" distros and hence have a better chance at getting a driver that works with it.
Cheers,
Kelvin