Can I create 2 partitions for ExHD to use with PC & DVR?

[EndoT800]

I have a WD500gb My Book Ext HD. I'm using right now with my DVR622. What I need to know if I can reformat the drive on my PC and create two 250gb partitions? One for the DVR and one to use with my PC? Not sure if the format that the DVR does removes the partitions and uses the entire drive anyway. I'm getting another 622 so I do not need all the extra storage on the ext HD. I would like to use part of the ext HD with my PC as well.

 

[8bitbytes]

The DVR will reformat the entire drive and recreate its two partitions.