Windows 7 is great... Coming from the dude who for the past 10 years refused to use an operating system other then XP.
If you want to try an alternate operating system that runs on extremely low system resources and leaves the entire system open to configuration in WHATEVER way you want, I'd definitely look into
Ubuntu...
Linux has never had an OS that I would advocate to the general PC user until Ubuntu came out. Honestly, All my computers are now running Windows 7 with a dual boot image Ubuntu. Whenever I want to do anything other then play games and browse the internet, I use Ubuntu. It's VERY user friendly, and you won't find another operating system that is more stable and runs on less system resources.
// end pro-linux / GNU rant
On topic, Windows 7 is SO MUCH BETTER then Vista it isn't even funny. Being a tech guru myself, you don't even want to have me start listing the reasons 7 is better then Vista... Honestly... Just take my word for it, go with 7.