I think you should get/use, at the very least, kernel 2.6.16 but I suggest 2.6.18.
I understand the reasons about using ancient kernels but you cannot do that and have modern hardware. Linux just does not work that way. Debian et al can only backport so much functionality...
NVRAID has to be setup in Linux using the device-mapper modules, aka ''dmraid'' as it is known. NVRAID 0, 1 & 0+1 have been supported for a while. The NVRAID 5 is supported but still not so easy. It is very new so it may not work... pretty complicated to setup too. I have not made it work yet.
Also, dmraid is not supported at boot by most distros so you cannot have any drives with NVRAID available until after the OS boots. YOU can make an initrd that will allow it but again, a little difficult.
I've been running NVRAID 0+1 for a few months using dmraid. No big problems and performance is okay/good considering the drives are (S)ATA.
There is some kind of issue with performance on files that are much greater than the total system memory... don't know why but that would rarely affect anybody. (Only hard core number crunchers, finite element analysis, copying/moving DVD images, etc.)
If you are not booting to MS OS & Linux or *BSD & Linux or whatever & Linux, perhaps it would be best to just use Linux SW raid. The multipath-device(md) modules work fine and the level of difficulty for setup is not too bad.
If you do need cross-OS compatibility, then NVRAID or an adapter card is the only way to go. You will need a recent kernel _and_ modules for that.
I forgot I had these links that might help you.
Linux Software RAID: http://www.sanitarium.net/golug/Linu...ware_RAID.html
Storage Review's reprint of PC Guide's old
RAID guide: http://www.storagereview.com/guide20...aid/index.html
( It still has valuable information about RAID even though quite a bit dated in some areas. )