Hello. My Dell Dimension C521's internal HDD has just about run out of space and I want to get a new HDD. Of course since its so slim I can't add it internally. So I was wondering whether or not I should get an external HDD or an internal HDD w/an external enclosure. Something else I'm considering is installing another OS in the new HDD. So I'd like to partition part of the drive for the OS (I'm considering a 500GB drive so about 150-200 would be for the new OS and the rest for extra storage for my current system). Would that be possible? And if so would it be easier on an external HDD, such as a WD Elements external HDD, or an internal HDD?