VirtualBox

From what I read it appears that VirtualBox is a viable alternative to VMWare, not to mention VirtualPC. The installation size is about 30MB, the performance is better to VMWare, the interface is less annoying than VMWare Server, and it supports both .vhd and .vmdk virtual disks! This means you can use both your VirtualPC and VMWare disk images.
The link above contains instructions on how to migrate an existing Windows machine or a virtual machine to a new VirtualBox virtual machine.

 

From my experience, the performance is very good. Software feels very lightweight and is easy to use and configure on the fly.

 

Hard disks

VirtualBox has a concept of storing all the hard drives together. The simple reason for this approach, instead of storing a hard drive together with a virtual machine, is that is supports differencing hard drive images. Some complex setups are available as a result of this.

I hope to test a setup where there is one installation of an operating system (for example, XP) and then there are differencing hard disk images that branch into a development disk and a personal disk.

As I read beforehand, it does read both .vhd and .vmdk drive images. I successfully ran a new virtual machine from both .vhd and .vmdk existing virtual drives.

Immutable images is a feature where a VM starts off an existing hard drive image but all the changes are stored in a separate file - a differencing disk.

It also supports snapshots. While I have had some issues creating snapshots with .vmdk files, the help file states:

"Initial support for VMDK was added with VirtualBox 1.4; since version 2.1, VirtualBox supports VMDK fully, meaning that you can create snapshots and use all the other advanced features described above for VDI images with VMDK also."

 

To convert between different virtual disk image types, use Qemu's img tool. Qemu for Windows available here.

VBoxManage is the command-line tool that is a part of VirtualBox installation and is used for various actions. One of them is conversion of virtual hard drive images.

Seamless Windows

VirtualBox supports Seamless Windows (source). This is a neat feature and means that you can have application windows from the virtual machine being displayed on your real machine!

Shared Folders

Shared folders are supported between the host and the virtual machine.

 

Many advanced tools are available through command line. While that might be a hassle, at least the functionality is there - compact virtual disks, create an immutable disk, etc.

 

To migrate an existing Windows installation or a virtual machine, follow the instructions posted here.