Installing more then 1 OS?

I would like a PC with Windows 7 Pro because the Pro version of Windows 7 has an XP mode, and it is the only way to lossless remove new DRM.

I'm not very familiar with PC gaming, so I don't really know how that works.

I actually dont have the second os right now. I just planned to use this thread for future reference for when I do get my 2nd os installed. I want to play some older pc games that wont work on windows 7. Lego racers 2, panzer elite action gold edition, and an off roading game that doesn't work at all on 7. This stuff worked fine on xp but wont run on a newer os. Lego racers 2 might run on 7 but the other two probably wont. I still have the off roading game from a long time ago that I used to play but it says incompatible application when I try to install it on 7. Apparently there's a sequel and that is supposed to work on 7. I dont have the sequel and have never played it but kind of want to.

Spirit Bomb - Don't worry mate, most of these games are fully compatible (the ones you mentioned are). I do recommend that, every time you install a new game, you give a quick look at its page in PC Gaming Wiki:

pcgamingwiki.com/wiki/Home

It's a wiki dedicated to solve any problems with pc games, including compatibility problems with older titles. Every older game I played until now had an usually simple solution to work on Windows 7/10, so I think there are very rare exceptions, like the ones mentioned by @lukefonfabre.

Spirit Bomb - I've been using Windows 10 since January. It's pretty much equal to W7, although I think it's faster (that may be a placebo effect, of course).

The only compatibility problem I've experienced since the upgrade from 7 was in Fortune Summoners: when played on fullscreen, the game gets really slow. The solution is either playing in its small window or lowering the desktop resolution so the window stretches to the entire screen. It's not much of a problem. Besides that, every game that ran on W7 has been working in W10.

About games that aren't fully compatible with W7/8/10, I just remembered an awesome indie one, Iji. In the last boss and a few other points, the game slows down to a crawl, getting almost unplayable. It's a shame, since the game is really good (think of a 2d game with the same depth as Deus Ex or System Shock 2). Luckily, the developer Daniel Remar is finally working on a much needed update.

Spirit Bomb - By the way, Iji is a free game and can only be downloaded on its own creator's website. Here it is, for anyone curious.

It's a highly recommended game, one of the deepest 2d action games I've ever played. You can even complete the entire game as a pacifist, and a lot of text and gameplay changes accordingly (even more than in the Deus Ex games themselves).