Even if your BIOS is up to snuff, you may run into hardware or software incompatibilities. Windows 8 is supposed to work with any hardware that runs on Windows 7, but older hardware may still be problematic. And software that requires driver-level access may have issues, too.
The easiest way to check out compatibility issues is to run Windows 8 setup. You can download the Windows 8 release preview, create a DVD (or install it to a USB flash memory key) and run Setup, making sure to answer 'yes' when the setup program asks you to download the latest version of setup. Note that you don't have to install Windows 8; the nice thing about the installation routine is that it first performs a compatibility check.
In this screenshot, the reported problem with the networking hardware spells trouble. I would definitely want to have a Windows 8 driver on hand before proceeding.
Upgrading to the right hardware
You need a new graphics card. Or the 19-inch, 1280-by-1024-pixel LCD panel you've been using for years is finally starting to fade. Or you're contemplating buying something as simple as a new mouse.
If you need to upgrade any piece of hardware, take time to research what will work best with Windows 8. Even if you don't plan on upgrading immediately, new hardware tends to offer better features, performance, or both. Let's look at a couple of examples.
Suppose that you have an older graphics card--say, an Nvidia GeForce GTX 260 or an AMD Radeon HD 4850. Neither runs current-generation games especially well, and both make more noise and consume more power than modern graphics cards. Currently, you can find tempting sale prices for one-generation-old GPUs such as Nvidia's GeForce GTX 460 or AMD's Radeon HD 6850. But if you're thinking of moving to Windows 8, it may make sense to consider a current-generation graphics card, such as the AMD Radeon HD 7970 or the Nvidia GeForce GTX 660 Ti. Both of those models support DirectX 11.1, which Windows 8 also supports.