What critiria for airport and RAID cards for Mac Pro (early 2008)

I have a Mac Pro that has both an external and an internal hard disc, neither of which show up in "About this Mac". So, I believe I'm in need of a RAID card. I think that i've read the RAID device should handle SATA 3, but that's it! I suspect that the RAID should meet more than just that. Could you tell me what I shouod specify?

Also, I can't see any evidence that I have an airport. When I look in "About this Mac", I can click on Wi-Fi and see 7 entries: CoreWLAN, CoreWLANKit, Menu Extra, System information, IO80211 Family, Diagnostics, and AirPort Utility. All of those entries have numbers beside them, which mean little to me. That last entry "AirPort Utility", makes me wonder - maybe I do have an airport at some undiscovered location. But, when I click on the fan shaped icon in the menu bar at the top of the screen, I get a "greyed out" message 'Wi-Fi: no hardware installed'. I know that airport cards are available, and I think from the evidence above that I need to get one. Can you tell me what critiria I should use in ordering the airport card?

PS It sees that I'm posting this request number times - every time I click on POST it re-opens