Administrators can convert a physical machine to a virtual desktop, but that process isn't always justified.
The process of converting a physical PC to a virtual one, whether it's hosted in a virtual machine locally or made available remotely, is common enough that there's an acronym for it: P2V, or physical-to-virtual. You most often see the term in connection with virtualized servers. Most of the time, P2V is part of a consolidation effort -- taking a bunch of legacy physical servers and putting them onto a single virtualization host.
But what about desktops?
Uses for desktop P2V
With desktops, a P2V effort is usually about moving people to a virtual desktop environment to preserve their existing applications with a minimal amount of disturbance to their work habits. People tend to set up a desktop system just the way they want it, with a specific application mix and settings and behaviors tweaked to their liking.
If users are rather unceremoniously dumped onto a VDI system that doesn't have any of that, it can be jarring. Worse, there may be cases where some applications can't be reinstalled properly on a virtual desktop instance, and the only way to keep them alive is to crate them up in the context of the desktop they're installed on. If that's the case, you may need a P2V migration from the physical PC to a virtual one, rather than simply spinning up virtual desktops on your new VDI software.
Still, a P2V migration is really only necessary as a last-ditch method to preserve the functionality of a desktop.
Consider these factors, and you may realize that you don't need a desktop P2V migration at all:
Applications. Apps (on Windows in particular) can be migrated to virtual desktops more easily than it might seem. A common reason for not being able to migrate the app is if the original installation media isn't present, but it is possible to use a program like RegFromApp to determine which Registry settings are accessed, then export those to a new target system.
More on P2V migration
Tools for P2V conversions
Tips for troubleshooting VMware Converter migrations
How to succeed with P2V migration
User settings. Settings and documents that are specific to individual users are extremely easy to migrate from one system to another without disrupting anything. A number of tools exist to do this, including Microsoft's Windows Easy Transfer, which can be set up to migrate settings and data very selectively.
Operating system. The OS itself can almost always be reinstalled anew, so you don't usually need to preserve the OS using a P2V migration. Earlier versions of Windows and their service packs are still readily available to IT managers if you want to install those on a brand-new virtual desktop.
Do you need P2V migration?
In short, most of what a P2V migration offers can be replicated through other means and with better end results. A piecemeal migration of apps, settings, documents and the OS to a new virtual machine not only provides a clean base to build on, but also allows the manager doing the migration (and the end user) to take a fresh look at all their work habits. Doing a P2V lets you pick up where you left off, but it also preserves any inefficiency of the existing setup on the desktop you're converting.
On the other hand, if time and uninterrupted service are of the essence, it makes sense to perform a desktop P2V migration for the sake of continuity. The user can always have that done first, then over time either migrate piecemeal to a new virtual desktop or start from scratch on whatever platform the organization has chosen for long-term VDI support.