Better for what exactly? Linux has the advantage of being free and is more customizable than Windows 7. Windows 7 has much better compatibility with a lot of software, especially with games. You really can't say one is better than the other overall, it comes down to what you use your computer for.
its arguable, all the linux os'es ive used have been all around faster, but im limited to arcade games, and a rather limited ammount of applications
but windows 7 is reasonably fast on most good systems, but has the majority of applications people use (sony vegas or vegas pro for example )... and has pretty much every new game release, and when it comes to viruses, it is much easier to get them than on a linux or mac system, but with the right precautions (a good antivirus which updates automatically) you shouldnt have a problem...
in my opinion, if you just wanna surf the web, and do other small tasks such as, just go with a linux based OS
For what it is worth, I use Linux on my older single core AMD laptop and my new dual core Intel Atom Netbook. The majority of what I do is internet based, so it really does not matter what OS you use. The internet does not care. Neither of these machine ran very well with the version of Windows that came on them.
My particular Linux distro of choice is an older one called Peppermint OS One. It is small and light, and makes my low powered portables feel like Core i7's. It is also sort of geared for internet use. All the apps in the start menu such as office, music player, etc. are internet based.
It also has a particular local app called Simple Scan that works very well with my old Canon scanner saving me the cost of replacing it because newer versions of Windows did not like it. And it also works well with my newer Samsung laser printer.
I do have a Windows 7 desktop machine for games, but that is about all I use it for.
What Linux is really good for is repurposing older hardware much as I have done. If you have an older computer laying around, you can pop a Linux distro on it for new life as a family web surfing box or some such.