I have two motherboards, MSI-6702 (64 bit single channel) and MSI-7511 (64 bit dual channel), I have two identical D-Link wireless cards and am running Kubuntu 10.10 on both systems. 7511 recognizes both wireless cards and connects to the Internet.The 6702 shows wireless grayed out on the connections page. The built-in Ethernet card has given out on both. I think I disabled it on the first system to have an Ethernet problem and wonder if I need to do it on the second. I would have tried it already but can' t remember how.

Umm. First I would check with MSI and see what the latest BIOS release is for each m/board.
If need be, I would probably install teh latest BIOS to ensure everything is to a know standard.
Prior to this of course I would read the "BIOS Change Logs" to see what exactly MSI updated or fixed.

I would bring up the BIOS on both machines and ensure that the on-board Ethernet are disabled and that
their IRQ can be assigned to other functions.

Now - your at a given know point. Now both systems should be able to handle the wireless cards.
If not, swap around the Wireless cards, to see if the problem follows them (you may have a faulty card).

From then on, you should be OK.
Cheers.

I would not be tempted to fool with bios just yet. Unless there is an exact quote from MSI that states your exact issue don't do it.

Since both wireless cards work in one system we have to assume it to be good at this point. That leaves me to suspect that you either need to blacklist the old wireless or properly install the new wireless or fix it settings.

Tools are lspci or maybe ifconfig or other kernel modules (modprobe) and maybe some others to give you a clue.