Despite having support for 64-bit operating systems, almost every new desktop PC sold today is shipped with a 32-bit OS. But over the next few years this will change. The change won't come about because users want 64-bit OSes or because vendors suddenly see the light. No, the change will happen because the unstoppable march of technology will force both users and vendors to adopt 64-bit.
I can see gamers demanding +6GB of address space within the next couple of yearsFirst off, a reality check. The reason that we aren't all running 64-bit operating systems (and Mac OS X users can stop being smug right now since the OS X kernel is still 32-bit) is that there's little in the way of immediate benefit. Bottom line is that you could take two identical hardware platforms and loaded, say, Vista 32-bit on one and Vista 64-bit on the other, and by looking at benchmark results you couldn't tell the difference between the two. In fact, the only difference that your average user would probably notice is that they have trouble getting some hardware to work properly because of driver issues. Driver issues is one of the main reasons why 64-bit Windows is being shunned by vendors (Apple get past this by having that 32-bit kernel). Who's going to take the chance that everything is going to work under a 64-bit when the upsides are vague? Not many people is the answer to that question. Even when you could make the switch, most people don't. Take me for example, I'm certain that I have a handful of desktop systems that are running 32-bit versions of Vista that could be switched to 64-bit, but I haven't done it.
I remember the revolution that Windows 95 was. Overnight, any piece of hardware that didn't have 32-bit drivers was considered obsolete and hardware manufacturers worked hard to make their drivers compatible. The move to 64-bit hasn't seen vendors enthusiastically embracing the new architecture because they don't need to. While Microsoft continues to release a 32-bit version of Windows, the urgency just isn't there ... yet.
What's going to kill the 32-bit OS isn't a new version of Windows (although if Microsoft were to release a 64-bit only version of Windows 7, that would certainly mean the end of 32-bit). No, what's going to kill 32-bit is the falling price of graphics cards and RAM. See, that 4GB of address space must have seemed like more that we'd ever need back when Windows 95 was released, but nowadays it is begining to feel awfully cramped. Back in 1995, the notion that we'd stick a gigabyte or two of RAM into systems seemed crazy, but now 2GB is fast becoming the norm and the price of RAM now means that you don't need to be a rock star to afford 4GB of RAM. That presents a problem when you only have 4GB of address space to begin with. In practice what this means is that you're throwing away at least 1GB of RAM to make room for everything else on the system that needs some address space.
But RAM isn't the only pressure on address space. Graphics cards are also consuming more and more address space. If your graphics card has 256MB or RAM, that's 256MB worth of address space consumed. If you have a card with 512MB of RAM, that's 512MB worth of address space gone. If your system is running a pair of NVIDIA GeForce Go 7950 GTX cards, each with 512MB on board, you've eaten up 1GB of space. 4GB of address space doesn't go far on a modern high-performance system. As you can see, it's not long before even mid-range systems start to feel the 4GB pinch. I can see gamers demanding +6GB of address space within the next couple of years. This means that hardware manufacturers and system vendors need to get their act together real soon and start to support and then actively promote 64-bit.
There is an upside to switching to 64-bit, and that is we won't have to make such a switch again for a very long time. As Jeff Atwood explains:
The transition from 16 to 32 bit increased our address space by a factor of 65 thousand. That's big. We've been in the 32-bit era since about 1992; that address space has been good for about thirty years, give or take a few. The transition from 32 to 64 bit, whenever we finally make it, will increase our address space by a factor of four billion. Will there be a transition to 128-bit machines and operating systems? Absolutely. But I'm not sure it'll happen while we're still alive.
So, maybe there's no time like the present to make the switch. In fact, I'm going to take my own advice and switch my main system (the quad-core system) over to 64-bit Windows Ultimate this week. I'll let you know how it goes.