From what I've read, you'll probably want to work with a copy of your VM file. The recommendations I've seen have said that you should remove the VMware tools from the VM file before you try to open it with Parallels, and then you'll need to install the Parallels Tools during it's first boot.
In the Parallels configuration I'd probably lower or turn off settings for different hardware's etc so that the VM comes up and installs the Parallels Tools automatically.
For my purposes, I'd just create a new fresh install of Windows on a Parallels VM and transfer the user files from one VM to another.
Essentially, you are trying to transfer Windows to a new computer with a new motherboard, Video card, sound, etc. The VM programs are the 'Machine' that windows set's itself up for. In the real world, with real hardware, this is already a mess and really never works right due to the Windows hardware checks, driver conflicts, etc. If it did work, then a VM program wouldn't be necessary on Windows machines, but that's why Microsoft bought Connectix.
In short, I wouldn't go the easy way you are trying to use as their really isn't a whole lot of support for each version of a VMware VM file to work with each version of Parallels. The same could be said for going the other way. When problems pop up you won't know if it's left over code from VMware, a bug in Parallels, or just Windows foolishness - or all three. Doesn't really sound stable enough for real work.
Good luck with that. 🙂