THERE IS NO GW-BASIC FOR WINDOWS 7!
I get this question to my contact form so often, I don't know why I haven't made a post or a page for it yet. GW-BASIC was last released in 1988 as you can see from any screenshot of its start screen. It's a 16-bit DOS executable that uses processor instructions no longer supported in modern, 64-bit CPU's / operating systems. Simply put: GW-BASIC.EXE cannot run directly on Windows! Don't lose hope, because this is where emulators come in. DOSBox is the premier DOS emulator with the best support and works on multiple platforms (I use it on Lubuntu Linux). You'll just need a passing knowledge of DOS and how a filesystem works, but otherwise running in an emulator is straight forward, like running a virtual PC from ye olden times inside your fancy new toy.