Never fear and don't listen to the naysayers. They make it sound impossible when it really isn't which just makes information on running Windows XP on a modern computer even more thin on the ground because it discourages people like you and me who dream of such a setup. For example, XP 64-bit isn't great, but it does exist. This guy had the same idea:
http://www.tomshardware.com/forum/id-3026670/building-absolute-fastest-computer-compatible-bit-windows.html while being more conservative with some of his hardware choices. As a matter of fact, there are still enthusiasts who go even further like those on hwbot running Windows XP on Skylake and X99 with GTX 980Ti's. GTX 7** cards were the last Nvidia officially supported, but Maxwell is the last gen where the drivers actually still work as shown in
https://www.youtube.com/watch?v=xwWrxu84hDw and http://mattpilz.com/windows-xp-drivers-nvidia-geforce-gtx-970-980-980-ti-titan-x/.
So the build you're after is possible (though I'm not sure about your insistence on Dell or HP OEM), but you're probably going to have to do it yourself unless you have a friend who just loves building systems and tinkering. If you want something done, you've got to do it yourself because people don't want to listen to the customer. The type of person that is after something like this is usually proficient by way of necessity because no one's willing to help them out just for nostalgia. The question is not whether it's feasible but whether it's worth your personal time and effort trawling XP holdout forum threads. If you do decide to go through with it, I hope to see the results.
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