What advantages does Linux have over Windows?
One of the main advantages of Linux over Windows is it's superior server capabilities. Linux can run very stable for month's at a time running services that bring a Windows machine to it's knees every other week. Windows has improved quite a bit, but Linux (or just about any Unix type system) is still far superior. Linux also has a very feature rich command line interface that a lot of techies prefer over using the standard point and click interface of Windows. I can do a lot more work in less time from the command line.
Linux is also perfect for developing software. All the free compilers and even free IDE's (Integrated Development Environments) are available now.
Linux is also a great learning tool. If you really want to know what makes your PC tick dig into the freely available OS source code. If you develop you own hardware you can easily write software for Linux that supports your new device.
In short Linux gives you many more options than even the most costly closed OS for little to no monetary cost and is far superior to Windows from a performance standpoint. Is it for everyone? Of course not. I like Linux because it is very useful for what I do. I have been working on Unix systems for almost 10 years now and I have become accustomed to the Unix interface as well.
You can get smaller disk images for Gentoo Linux, but it is a lot trickier to setup than the commercially supported versions like Redhat. The best thing to do with Redhat is just go out and buy the disk at your local software store. It comes with an easy to use installer and can be installed in less than 30 minutes.