Windows – Can all computers running Windows 7 Professional run Windows XP mode

I am a little confused about what XP mode in Windows 7 (Professional) even is. XP mode seems to be a mode in which you can run XP-compatible applications that are otherwise incompatible with Windows 7. The web seems to say that XP mode is a downloadable add-on that, in theory, works with any version of Windows 7 — provided that you have a processor that supports hardware visualization.

What I don't understand as I price various Windows 7 Professional laptops (my first) is why some models appear to come with XP mode, whereas others do not. For example, the XPS line of Dell laptops does not appear to come with (nor be compatible with?) XP mode — see, for example, this page on Dell's site. If you configure one of these machines, there is no mention anywhere that I can see of XP mode. On the other hand, the Latitude line of Dell laptops does mention XP mode — see, for example, this page. You can choose to include XP mode, and you even have your choice of 32- or 64-bit OS.

Is there any reason for this difference? The processors and video cards available for these systems seem very comparable. Do you think it would be wise to select a system with XP mode preinstalled, or do you think that installing XP mode on my own, from the web, could be difficult because of potential incompatibilities with the processor and/or video card?

Thanks for your time!