I know this isn't exactly the most appealing suggestions, but have you tried a clean Windows install? I'm wondering if using an nLited version may have something to do with it.
I'm one of the people around here who have had some issues with the performance of the stock WLAN card, but I don't see why something specific to the Mini would interfere with your 4965 card. My mind is pointing toward software.
Also, check in msconfig if igfx* is loading at startup. The A04 BIOS fixed the resolution issue everyone was having, so I wonder what is causing your problems.
Wait, re-reading your post makes me wonder: in your nLite CD, did you remove anything from Windows, or just add the one driver?