Are you considering making a migration from Windows to Linux? Are you worried about losing any Windows programs or functionality?
There are two very important pieces of software that I would like to touch on, that can really help in making the migration and to also avoid setting up a dual booting machine (having a bootloader to boot in to Windows or Linux).
If you need one or two basic Windows programs, that don't need to interface with a lot of hardware, I would suggest giving Wine a try. Wine is really a neat piece of software, that gives programs access to certain Windows binaries and libraries so that the program can run on a Linux machine. The older the program is for Windows, the better luck you will probably have of running it with Wine, even if it was meant for Windows 3.1. Which is ironic as that is usually the opposite of how it goes in native Windows, where running older programs is a challenge. Wine has a LOT of options that can be set for each individual program that you need to run, including what Windows version to emulate, sound options, libraries, and other environment settings.
If you can't get Wine to run your Windows program, you will probably be faced with setting up a virtual machine to emulate a running Windows computer. It is a little bit of work as it requires all of the steps required to install Windows on a brand new computer. But, after you do it the first time, you can copy and move the virtual machine to other computers, so the step should be a one time deal and it's good to go. I highly recommend VirtualBox for handling virtual machines on the Linux desktop. It's extremely simple to use, yet powerful and very scalable as well. It also interfaces with USB devices flawlessly. This means if you have an old camera or scanner, and you really prefer the Windows drivers or utilities, you can open up a Windows virtual machine in VirtualBox and run those programs, and they will interface with your scanner just as if you were running on a real Windows PC. There are additional benefits of using virtual machines, such as taking snapshots. VirtualBox supports this and it's perfect if you need to test out some things and then want to roll back to a previous state. VirtualBox 3.x also supports 2D and 3D acceleration which I will be testing out soon. And one final feature that adds the finishing touch to VirtualBox is it's "seamless" mode. In Gnome, this adds the Windows taskbar next to the Gnome application bar. But, your regular Gnome desktop is also retained. This allows you to launch Windows applications inside your virtual machine, and they will appear to run in their own windows in the Gnome environment. That way windows can be minimized and moved around, etc.
So fear not if you are considering making the plunge over to Linux. There are tools in place that will allow you to make the switch, yet retain Windows for niche applications if you need them.