Linux OS

well, personally I dual-boot with Linux, so what I use is really more of a contained Linux that I run while also running Windows, if you know what I mean. Anyways, http://www.andlinux.org/ is a very useful version, and I believe it uses the BASH shell, but you can change that obviously

There are so many websites and companies that are providing Linux OS. For example, Redhat, Mandriva, Ubuntu, knoppix, etc. choose the best that fits to your needs and then you can download the OS from company websites directly. I prefer Mandriva Linux OS because it is easy to use than other OS. You can download it from http://www.mandriva.com

My advice, go here: http://distrowatch.com/ check out the different distributions and see which is right for you and your needs. I think you will find that a valuable resource.

It depends which distribution you want. Since I assume you are inexperienced user, I suggest downloading either Mandriva (www.mandriva.com) or Ubuntu (www.ubuntu.com). These two are the easiest to use and most widely supported. In case you do not want to part from your Windows, but still want to use BSD/Linux distribution, I suggest using a live distro. This means that you do not install the operating system on your hard disk, but instead the OS is executed directly from a bootable disk or USB. You can find a huge list at www.livecdlist.com. Hope this helps you :)