Glad to hear you resolved this issue. If its the second stick of memory thats causing the problem, I would not use it at all. Who knows what other types of problems or data corruption it might cause down the line. As for FC6 vs Ubuntu, thats a personal choice. I like Debian based over Red Hat based distros, but if it was up to me Id use Arch or Slackware.

I am glad this was the good suggestion

Install kernel are sometimes/often different to the running kernel, that is why I suggested to halve the memory. If you swap one stick for another, you could check everything is still fine.

Is the pair well matched?
Check the bios is not underpowering (low voltage) the memory. Some bios are overcautious and do that

It seems to be running well with both sticks of RAM in the system, been up for 3 days, and I am posting this from Linux

I have it set up that Windows XP is installed on my 2x100gb SATA RAID 0, and Linux is on a 40gb IDE drive.

Problem I am having is with the dual-boot. If I set the BIOS to boot off SATA first, it goes right to Windows without even seeing the Linux drive. Which is the way it should be. If I set the BIOS to boot off the IDE drive, it load GRUB, which sees the Linux and the Windows installations, it will boot to Linux fine, but does not boot to Windows.

The GRUB files list Windows as booting off hda1, which I think is wrong. Do I need to change it to sdb1 which is the SATA correct? Or is there more too it. I don't want to screw around with it too much as it too me a long time to get to this point, and don't want to go backwards, haha.

Thanks again for all the help.

The hdX is for IDE drives so if your Windows partition is the first on the second disk then it couldn't hurt to change hda1 to sdb1 in Grub. I've never actually used SATA or RAID but I'm pretty sure that there isn't much of a chance of working if the SATA drive is being called as hd instead of sd.

Just to lift any confusion for anybody reading this thread being in doubt, grub does not call hdX or sdX "per se"/ or with a special syntax for each type of HD. I am sure the posters are clear, it is just might be confusing for newbies.
in grub's speak any HD is hd(x,y)
where x is the HD number (be it sata or ide or usb)
starting from 0. So all HDs are numbered from 0 to n.
partition is y (starting from 0)

Grub may see the Sata RAID as two separate disks.