I would be careful with Windows 8... Many Game developers have voiced their concern that it will not be the open platform anymore, that windows used to be. Apparently there are rumors that Windows is planning to go the Appstore-route and games will only be available through the Windows store. So I wouldn't be surprised if it was impossible to install older games due to lack of activation possibilities or the like... but then I've also heard conflicting news that said that the store will only come as an addition to the "normal" way to buy and install games...
Don't take my word for it though, I'm not an expert. Here, have a look at this and form your own opinion.
http://www.escapistmagazine.com/news/vie...s-8-Chorus
To make a long story short, as long as its still possible to install Windows 7 on a new PC, I won't get Windows 8. There's definitely something fishy about it...