Virtual PC is able to save the current state of the PC running, whihc means that you can save, quit Virtual PC and then go back to it from where you left off. You don't have to boot the PC again. That would be a great feature to have in Parallels' Workstation.
Might want to give the old help file a try: State of the running Virtual Machine with all its applications inside can be saved to disk for continuing executing guest OS at a later time. This is called suspending of the Virtual Machine. When suspending, Virtual Machine state is saved to hard disk in a .sav file. After this no matter how long you will not touch it, will you shut down your host computer or not, you may return to the saved Virtual Machine at any time and continue running the guest OS from the point where you stopped. You may configure Parallels Workstation so that all the Virtual Machines will be suspended when you press the Power Off button, or so that you will be asked whether you want to suspend or to power off the Virtual Machine on this action.
Give user a choice when quitting My suggestion then is to rename the choice Suspend to Save State instead in the dialog box when one quits Parallels workstation without powering down the virtual machine. This would ease the transition that Virtual PC users have to make when migrating to Parallels. I would also make that dialog box look more like a Mac OS X dialog box with three aqua buttons
