Here's the TL;DR version of this article: it is possible to upgrade an old XP machine to Windows 8 Pro. The key things to keep in mind are your machine needs to be properly prepared for the upgrade and drivers are a hassle.
Okay, so now the rest of the story.
Here at Camp David, we have a bunch of computers. My main office desktop is an uber-tricked out machine running 32GB of RAM and big, gloriously fast SSDs. It runs Windows 7 and will probably keep running Windows 7 because it works well and there's no reason to make any changes.
On the other hand, the machine in my study (a quiet room in the west wing — yes, we have a small wing of the house that faces west) is a leftover from a bygone day. I don't use that machine all that often and when I need to do real work, I use my main machine or my Windows 8-running Mac mini in our media room (which is what I'm writing on right now).
The machine in my study is a Zotac MAG I purchased from Amazon back in 2010. It runs a 1.6 GHz Intel Atom 330 processor, 2 GB of DDR2-800 RAM, a very slow 160 GB SATA hard drive. The machine has three saving graces: (1) I own it, (2) it was cheap even back when I bought it, and (3) it's tiny, about the size of a Mac mini (but with a fraction of the power).
Anyway, after writing a lot about the need to upgrade to Windows 8 and recalling Jason Perlow's Installing Windows 8 on your old PC could turn it into Greased Lightning, I decided to see if I could breathe some new life into the old Zotac.
My alternative was to get another Mac mini and put Windows 8 on it (these are proving to be great, tiny Windows machines at a good price), but I still really didn't want to spend the cash if I could help it. I had a spare $40 license to Windows 8 Pro (which I bought last year) and using what I already had would definitely be cheaper than spending a grand on another tricked-out Mac mini.
My ZDNet colleague Ed Bott recommends the Intel NUC as a great alternative to the Mac mini. He says it's smaller, half the price, runs great, and is built for Windows. This is definitely a machine I'm putting on my Christmas list for a future upgrade, especially since it supports up to 16GB of RAM, although unlike the Mac mini server's i7, the NUC only has an i3. On the other hand, it is substantially less costly.
Tip #1: It's easier upgrading a newer XP machine
It's important to remember that the Zotac was anemic when I bought it. It was cheap. Period. But it's also important to remember that it's an XP machine that was built relatively late in XP's lifecycle, which means there was a better chance I'd find modern drivers than for a machine built back in 2003 or 2004.
So, here's your first tip: if you're running a more modern XP machine, you have a better chance of succeeding than if your machine came from way back in the day.
Also, as Ed points out, you should check the list of Microsoft's supported upgrade paths before getting started. Ed also points out, "Your CPU must have support for PAE, NX, and SSE2. If it doesn’t, you can’t install Windows 8 at all. I had a few machines around the 2005 era, many of whose brethren are still running today, that don’t qualify." You can read this Microsoft technical document for more info on those restrictions.
Obviously, you should check restrictions out before you attempt your upgrade, because my experience has been that once you start a Windows 8 upgrade, there's no turning back unless you decide to fully reinstall XP (yep, did that on one machine).
Oh, and before I move on, it's also important to note that if your machine is already handicapped by slow RAM and a paltry processor, nothing will make it "greased lighting". That said, the finished machine is pretty tolerable.
Tip #2: Upgrading will zorch your apps
I really didn't have much running on this machine. I had Office, but the files are all stored on our central media server. I had Chrome, but Chome syncs everything beautifully. I ran Netflix from within Chrome. And that was about it.
I never tried to put my programming environment or my graphics tools, or VirtualBox, or anything else on the Zotac. It was for simple writing and Web browsing.
If you're upgrading an XP machine that's chock-full of applications, you need to know that those applications will not be available from within Windows 8. Windows 8 will, theoretically, preserve your documents, but you will need to reinstall your applications.
Tip #3: Backup as though you were formatting to bare metal
Ed points out that you're really not "upgrading" XP at all. You're really running an installer that's doing a clean install of Windows 8, simply preserving your documents. In that vein, Ed recommended (and I may still do it), that you just swap out a slow HD for an SSD (or keep the HD and use it as a data drive) and see how far that takes you. It's a good suggestion and if I wasn't running in "how cheap can we do this for" mode, I probably would have tried it on this machine.
That brings me to the third tip. After doing a bunch of Windows 8 upgrades on a number of different machines, I've become aware that if Windows 8 fails to complete its upgrade, it may leave your machine in an indeterminate (i.e., broken) state.
The best practice is to back everything up as if you're planning to format your drives back to bare metal, because that may well be what you do. Don't assume it will work on the first try. It probably won't.
Tip #4: Be sure you're running SP3 on XP first
Sigh. What is it with Microsoft? Sigh.
Okay, okay. Deep breath. It's not particularly hard to upgrade to Windows 8, but there's something wrong with the water the folks in Redmond drink. Let me give you two examples, which will also help you succeed in your upgrade.
I moved over the installation files onto the Zotac, and double-clicked the .EXE file. After a moment or two, I got this message: "This platform is not supported."
No, wait... huh? I thought XP was supported as upgradeable to Windows 8. A little digging proved it was. So, what's with "This platform is not supported"? Okay, maybe because I'm running a crappy little Atom processor, the Atom processor isn't supported. More digging. It certainly is supported.
The answer to this mystery, plus many other XP-to-Windows 8 tips are on the next page...