You can use ESATA or USB(3.0 if you have it) to get access to the drive on your system. You will still need a power supply. Many USB 2.0 and 3.0 to IDE or SATA(make sure your drive is a match) adapters come with a power supply for the hard drive.
Now I do not know what format the system uses, so you computer may not actually be able to see the file system.
Contacting Nightowl may be a better option first to ensure the device uses a file/drive format windows can even recognize. After all you can not pull a drive from a PVR and always have it work in Windows.