Re: Hardware advice

Yeah, it sounds like you are having to wait for the media to come across a slow LAN connection. You're current processor should handle that fine, but I'm not sure what codec the Nikon uses - I understand that it is in an avi wrapper though. Some codecs can be more difficult to process than others, like HDV.
The drive you pointed out is pretty small capacity, you may be able to get double that for a fraction more. But then you'll want to copy files from your NAS to the local HDD, then copy your finished project and files to the NAS. You don't want to leave anything sitting on a single drive because it will eventually fail.
Good Luck!
TC