As much as I personally love XP, Windows 7 is a better OS for running "modern" games, simply because it gives you full support for things like DX10/11 and 64-bit apps, and a lot of games nowadays aren't even written with XP compatibility in mind. The "phoning home" aspect of the OS may not sound that great, but really, it's rather insignificant. Google and Facebook do their fair share of data mining as it is, and nowadays, I'd say they scare me more than Microsoft, but I still use their products.
The tricky thing about running Windows 7 is the licensing, since it's been toughened up a lot since XP, and there aren't really any *ahem* good ways around it. 😉 Also, it's hard to get a legit copy of it anymore, since Micro$oft in their infinite genius has decided to stop selling retail copies. You may still be able to pick up OEM copies from sites like Newegg, but I do not know for certain.
Now, OEMs are still allowed to sell systems with Windows 7 preinstalled for about another year, so what you could do is go through a company like iBuyPower, and get them to build you a custom rig with Windows 7 preinstalled. It's not as fun as building your own rig, but you still get to choose most of the parts that go in, and it's your surest bet for having a new machine with Win7.
If you decide to buy from an OEM that doesn't provide Win7, what you could do is get a machine with 8.1 Professional installed, then use the downgrade rights to downgrade to 7 Professional. Note that this only works with machines that come with 8.1 Professional preinstalled, NOT if you buy your own copy of 8.1 Professional. Microsoft explains the 8.1 Professional downgrade rights here: http://www.microsoft.com/oem/en/licensing/sbl … ade_rights.aspx
One more thing, if you end up with a machine that has Windows 7 installed, but with no installation discs, Microsoft actually provides officially-hosted isos of these discs. Make sure you have a legit product key before you use them, of course. They don't come with any sort of modifications. http://www.techverse.net/download-windows-7-i … ficial-servers/