It seems that some of you who have downloaded the Windows 7 beta 1 .ISO file are a little uncertain as to what to do with that .ISO file. Fear not, here's a quick rundown to get you going!
See also: Windows 8 Consumer Preview vs. Windows 7: Benchmarked
#1 - Download the Windows 7 Beta 1 .ISO file!
Well duh! Save it somewhere easy to get to (like your desktop).
#2 - Download and install ImgBurn
Rather that try muddling through with burning the .ISO file with whatever tools you might already have installed, download ImgBurn and use that. That way we're all on the same page!
#3 - Burn the .ISO file to DVD
OK, pop a blank DVD into your DVD writer drive (for now I'm assuming that you actually have a DVD writer, if you don't I'll show you something else you can do in a moment). With that done, fire up ImgBurn. Select Write image file to disc.
Point the Source to the .ISO file you downloaded and then click on the big button at the bottom-left of the window to kick off the disc writing process.
And then after a short wait, you're done!
Now you've successfully burned the .ISO file to the DVD ... congratulations!
#4 - Use the DVD
You can now use the DVD like any other OS install disc ... pop it in the DVD drive of the system you want to install Windows 7 onto and boot up the PC and you should get that Press any key to boot from CD or DVD message. Press any key to kick off the proceedings!
Note: If you don't get that Press any key to boot from CD or DVD message then you'll need to dig out your motherboard manual and twiddle with the boot device settings.
What if you haven't got a DVD burner or just don't want to hand over an entire machine to Windows 7 beta testing? Are you stuck? Nope! You have two options:
Option #1 - Dual boot
Lifehackerhas a good post on how to do this.
Option #2 - Go virtual!
Why give over an entire PC to a single OS when most are powerful enough to run two OSes side-by-side. To do this download and install Microsoft's free Virtual PC 2007. Once you've installed it run the application and it will guide you through creating a new virtual machine.
Most of the default settings will work for you but when asked for the operating system, pick Windows Vista, and when asked about virtual hard disk options, create a new virtual hard disk. Then, from the Virtual PC Console select the virtual machine you created and click on Start. As soon as the virtual machine fires up, click on CD from the menu and choose Capture ISO Image ... and select the Windows 7 .ISO and click Open. Now click on Action and then Reset to kick off the Windows 7 install process.