Well, let's start with can your computer handle it?
You need to have these specs as a minimum.
- 1024x768 monitor (yes, it will run on as low as 800x600, but you won't like the experience as all of the new apps need at least 1024x768)
- 1366×768 resolution if you want the snapping feature
- 1 GHz (with PAE, NX and SSE2 support) sure, most people have that, but some might not.
- 1GB RAM (2GB if using the 64 bit version)
- DirectX 9 capable video card
- 20GB of Hard disk space
Now there is the whole start menu issue. Windows 8 doesn't have one, at least not in the traditional sense. It just throws all of the start menu icons onto a Start Screen that looks very much like a tablet screen and doesn't bother to sort them into folders. This can be annoying.
Realistically, Win 8's interface is designed to be used with a touch screen, so yes, it can be used with a mouse and keyboard, but you will find that you use the keyboard far more often now if you choose to use it this way. You can't click the start button for instance, because there is no onscreen start button, you use the keyboard or a touch gesture to get to the start screen from the desktop.
Be prepared for some programs to not work in Windows 8. Just like any major Windows release, not all of your old software will work with the new OS. But, sometimes that is a blessing in disguise. I wanted to download MS Security Essentials for a Win 8 box I have, but found that there is no version for 8. That's because they re-named it Windows Defender and included it by default. Go MS! Finally you have done that right.
If you are a techie and want to run it in a Virtual machine first, (If you are a techie why has it taken till now for you to get around to installing it??) you should know it cannot run on Microsoft Virtual PC, Windows Virtual PC, Microsoft Virtual Server or VMware Workstation v7.x or earlier. It should run ok on newer VM environments though.
To check if your PC meets all of the requirements, you can run the Upgrade Assistant from Microsoft.
If you are looking for the cheapest way to get it you can Download Pro for $39.99 directly from Microsoft. Then you just burn your own DVD-ROM of it just like Microsoft's corporate customers have been doing for ages, and away you go.