Relative newbie needs help getting network working

[Frank W. Zammetti (MLists)]

Hello all.  I am a fairly new Linux user.. I have some experience, but
assume I know almost nothing...  I have set up and used a couple of
different distros over the past 2 years or so, but I'm pretty much still a
newbie.

Anyway... I have a Dell Optiplex GX1 that I'm trying to set up.  I
originally had Mandrake on it, I forget which version (if not the latest
than just 1 or 2 versions back).  Problem was, networking was not working.
 When it booted the eth0 initialization would fail and it said something
about a possible cable problem.

Well, the machine was set up as a dual-boot with Windows 2000, so I booted
to Windows and networking was working just fine, so I know the cable is
fine.

I decided that maybe installing the latest RedHat would take care of it. 
So, I installed 9.2, installing everything (as I always do because I
frankly don't know what dependencies I might screw up if I'm selective!). 
The install went smoothly, it identified the network adapter correctly (an
onboard 3Com, 3C905 I believe), no errors, seemed to be OK.  But, when I
booted, the same problem as with Mandrake happened.

I got into a GUI (I assume it's KDE, I'm not really sure, it's all
RedHat-branded) and selected the Networking option from the System
Settings menu.  I selected the device (which it says is inactive,
logically) and clicked Edit.  I noticed on the Hardware Device tab the
Bind to MAC Address option.  Now, I'm not sure if this is important or
not, but I noticed there was a Probe button, so I clicked it.  It came up
with a MAC address, so my conclusion is that the OS is indeed talking to
the network adapter properly.

So, at this point I'm at the end of my knowledge.  Any ideas on what could
look like a cable failure to the OS but actually NOT be?  The only
remotely unusual thing I can think of is that we use Cat6 cabling here. 
Any chance that's an issue in some way I can't think of?

Also, it is set up for DHCP.  DHCP is active on the network, as evidenced
by the fact that I can plug my laptop into the network using the SAME
cable as this PC and I pull a DHCP lease and have access to the network.

I'm at a loss and would appreciate any help you can give.  Thank you!

Frank