Tried to install Fedora 7 on an IBM x360 server with 4Mx RAID card.

The Live CD says:

Buffer I/O error on device sr0, logical block 341174
SQUASHF error sb-bread failed reading block 0xa6911
unable to read page
Bug: soft lock up detected on CPU#0

CentOS CD boots fine. So is Red hat Linux 9.

My main concern, since I am a dummy in Linux, is CentOS a good version like Fedora? I like to install a popular version obviously.

What version of CentOS are you running. RedHat 9 would have a 2.4 kernel whereas Fedora versions 4 and higher have a 2.6 kernel.

There are older RAID cards in the world that aren't supported in the 2.6 kernel so if the CentOS you tried had a 2.4 kernel and it and the RH 9 both worked it would suggest that is your issue.

CentOS, RedHat and Fedora are all related. RedHat (after 9 it is called RedHat EL/ES) is the commercial software sold by that company. Fedora is the non-commercial distribution that is used as a testbed for what ends up in RedHat EL/ES. CentOS is a compile of the source used from the commercial RedHat so is free like Fedora.

I've only used Fedora and RedHat (in this family - I've used Debian as well but that is in the same family as Ubuntu so somewhat different). Many folks will tell you they prefer CentOS over Fedora because it doesn't force you to upgrade as often as Fedora.

To determine the kernel version just type "uname -a" once you're at a system prompt. The kernel will appear in the output (usually something like 2.4.3.2.5.SMP...) the first two characters tell you the major kernel release (2.4 or 2.6). There are significant differences between 2.4 and 2.6.

Both are the latest. I just downloaded them last night.