How do I get 32-bit software to run on 64-bit Windows?

It (Mostly) Just Works

In my experience, most 32-bit software "just works" in 64-bit Windows 7.

Yes, I did say "most", so there are exceptions, but in my experience they're actually not nearly as many as you might think.

I certainly would not get any "free downloadable programs" to somehow get 32-bit software to work, since as I said - most pretty much work already. I'd be very concerned that those downloads are something else - perhaps malware or perhaps trialware that leads you to eventually pay for software that you just don't need.

Windows on Windows (32!)

The processor - the actual CPU itself - actually has the ability to work in either 64-bit mode and 32-bit mode. In fact, believe it or not, for extreme backwards compatibility it also still handles 16-bit mode.

And it can switch between those modes "on the fly".

64-bit Windows manages all this by transparently changing the mode as needed. In fact, there's an interface layer called WOW32 - Windows on Windows - that provides a 32-bit interface to the 64-bit OS for 32-bit applications and handles that translation between 32 and 64 bits. (Once upon a time there was also a WOW16.) Since the Windows itself is 64 bits, that translation needs to happen as activities are handled and passed off between the 64-bit operating system and the 32-bit applications. (64-bit native applications don't need this translation layer. It's not an obvious performance win, though, for reasons beyond the scope of this discussion.)

One thing that this means is that the vast majority of software out there is still 32-bit software, including some of the software that comes with 64-bit Windows itself. Aside from drivers and such, which I'll talk about in a moment, there's not really been a pressing need to convert most applications to 64-bit - unless they were bumping up to some limitation like RAM access that a 64-bit conversion would benefit, or compatibility with some other software that has been converted.

The result? Pretty much everything I had running on my 32-bit Windows XP machine is now running seamlessly on my 64-bit Windows 7 machine without any additional effort. Case in point: I'm typing this article in a 32-bit application (Topstyle) on my laptop running 64-bit Windows 7 - there were no steps I needed to take to make that work, and certainly no software to download.

In fact, after a few additional installs and upgrades I'd be hard pressed to tell you which are 32-bit and which are 64-bit applications without firing up a utility of some sort to examine them and tell me. They all just work and that's what matters.

64-bit Exceptions

There are some exceptions, of course - the most obvious being device drivers.

The 64-bit operating system itself is ... well ... 64-bits. Device drivers are part of the operating system and thus need (*) to be converted to 64-bits. That's part of why 64-bit OS's took a while even though the processors were ready and deployed and why some hardware drivers still aren't available for 64-bit OS's and may never be.

(*) There may be hacks for some types of drivers that might side step this requirement, but in general drivers need to be 64-bit native in 64-bit OS's.

Other exceptions typically boil down to updates of existing applications. For example, Windows 7 comes with both 32-bit and 64-bit versions of Internet Explorer. I recently updated to a 64-bit version of Adobe PhotoShop so that it could better take advantage of the available memory on my machine when processing large images.

But these are updates to existing versions. In many - if not most - cases, the prior 32-bit version would also work acceptably well.

In fact, specifically in Internet Explorer's case, the 32-bit version is perhaps the preferred of the two simply because 64-bit support is not yet available for many popular plugins.

And of course there are applications that, by design or by accident, simply make assumptions of one sort or another that are valid in Windows 32-bit but are not in Windows 64-bit, even when running in WOW32. Those are few and far between, in my experience, and probably warrant an upgrade of the application rather than some "free download".

When All Else Fails

Microsoft did something very interesting with Windows 7 versions "Pro" and better; if your hardware supports it you can get Windows XP "mode" as a free download. XP Mode is a copy of Windows XP that you run within a window inside of Windows 7. Within that copy of Windows XP you can run whatever it was that used to work in Windows XP but for whatever reason fails to run in Windows 7. It's not completely seamless, but it is a solution for many situations where software updates are simply no longer an option.

That's the only "free download" I'd even consider.