My machine from Nov 2007 is 32 bit. It was a high-end system back then, designed to run AutoCAD, Photoshop, both at the same time even. Last year I reformatted the hard drive with the operating system (prefer my desktops to have two internal hard drives - one for the operating system and one for my files) and loaded Windows 7. Cleaning up the operating system by getting rid of the seven years of Windows updates made a huge difference. It runs just fine and is the computer my average computer-user hubby uses now.
I have a newer 64-bit high end desktop, again because I multi-task with numerous memory-hog programs open at a time. And I don't mind getting on my old computer (his computer) at all - it does everything well, and doesn't feel slow.
And it also is compatible with a piece of hardware I have (an old Hauppauge PVR) that won't work with my 64-bit system. So if I want to record an old VHS tape to digital, I use the 32-bit system with my vintage VHS player and the Hauppauge.