Great discussion, really helped me get my head round it, and i’m still not sure if i have. lol
i have an asus A8V Mobo, AMD 4200 x2, and 4gb RAM, and vista 64, if i enable “memory hole” in the bios i get to see all the ram, had to back peddle a few bios versions to achieve this without an in built by asus apparantly, USB error (put in to safe guard the system from “possible” crashes apparantly, gee thanks asus.
so i get to see all the memory, i boot to vista 64 (its definately a slower boot) vista sees all the mem to, but the nic doesn’t work, no conflicts or errors, just says no cable is plugged in, and thats that.
have to admit though, i love the feel of vista 64, everything i need works with it, and even though i only see 3456mb i’m sold 
however if anyone knows how to remap a “Marvel Yukon” NIC’s addresses i’d be interested to hear about it.