windows 7 and Mac are operating systems, not browsers. Google Chrome, Internet Explorer, and Firefox are examples of browsers.
I am running 32-bit Windows 7, and I rather like it. I will be upgrading to 64-bit soon. In the past, I've used Mac OSX, and I absolutely hated it! Things were constantly going wrong, I hated the interface, and it was a piece of junk. I've learned that Mac is okay for people who don't want to make any modifications with their computer. PCs allow you to upgrade, make modifications, and do all sorts of special things, but Macs don't really let you do that. Yes, it's possible, but they make it a lot harder for you. If a computer takes over the world some day, it'll be the offspring of a Macintosh, since you can't really control it.