Yes, a DVD-ROM drive. In other words, a drive that can burn data to a recordable DVD disc.
You need that because Microsoft's not providing the beta as an executable or installation file, but as a disk image, or .iso file. Once you've downloaded the monster, you must burn the image to a DVD to create the installation disk. That means you need DVD-burning software, such as Nero 9, an US$80 download from Nero AG, or the $100 Roxio Creator 2009 from Sonic Solutions.
There are also plenty of for-free DVD-burning programs out there; Microsoft recommended ImgBurn, which you can download here.
That's it? Nothing else?
Last thing, we swear. The Windows 7 beta is actually an upgrade, not a full new install. You need to have a machine running Windows Vista Service Pack 1 (SP1) to install the beta.
So if you're still running Windows XP -- which a lot of people are, what with Vista's problems, real or imagined -- you're up a creek sans the proverbial paddle.
Is Microsoft limiting the beta?
Yes it is. The company said it will close out the beta after 2.5 million downloads.
Really? So if I'm late to the party, I'm out of luck?
Not really. The 2.5 million number is how many activation keys Microsoft will hand out to beta testers, not the number of actual downloads. (Yes, Windows 7 retains product activation.)
Microsoft won't pull the download after the 2.5 million, it will just stop handing out keys.
Minus a key, you can still download and install the beta, then run it for 30 days before it quits on you. And by using the same "slmgr -rearm" command that gained notoriety after Windows Vista's debut, you can extend that trial period to 120 days.
Several blogs have posted instructions on how to use this legal method to extend the lifespan of Windows 7 previews, including "My Digital Life."