You can boot the VM from a liveCD ISO and then mount the drives to extract files (share a USB storage device to easily get them off). You could also add a second virtual disk, put an NTFS partition on it (within the VM) and copy to that if you plan to rebuild the OS drive.
If you need the offsets of the partitions you could also mount them from the disk image directly via a loopback device, but that’s a bit more complicated.
When dealing with Windows either on bare metal or VMs, I’ve often found it useful to store my more important data on a second disk so that I can easily back it up and it will survive across a wipe+reinstall of the OS.