sorry .. yes .. my t5400 came with vista business 64bit... i want to upgrade to windows 7 professional. i tried the upgrade, on top of the vista install, and ended up with blue screen and the message stating basically there was a timing issue with "one" of the processors.. as you will see in device manager, windows shows 8 processors (being 2 cpu's quad) .. maybe not related, as vista shows the same.
i just tried a fresh / clean install of windows 7 ... not an upgrade, but just windows 7 from the cd .. still the same thing .. i blue screen almost right away..
so i think this is a bios issue with the dell (intel) mother board and / or cpu's so i am stuck until dell or intell addresses i suppose.
i am running the current a04 bios from the dell website .
glad to hear you have no issues.. enjoy your system