I assume by "rip without the menus and extra audio Just the dts Audio and movie" you mean a stripped rip and not transcoding? I hate to break it to you, but your Dlink NAS is just not going to cut the mustard. Realistically, you're looking at ~6TB for your DVDs plus 2-2.5TB for your BD rips. So figure on needing a
minimum of 9TB to account for margin of error and to give you a bit of room for new titles. That's not even counting some sort of redundancy. Obviously the back end is going to be the biggest and most expensive part of this setup, so you should really get that sorted out before you decide on a front end.
Getting another NAS (or two, or three) is an option, but a
much better, long-term solution is to set up a dedicated file server. A server will give you a more control over your collection, and will be a heck of a lot more expandable. For servers, you have three choices again:
Windows Home Server : Very easy to set up and maintain. All drives are pooled together and show up as one big empty space into which you can put all your media. You can add or remove drives of any size at any time. If you run out of room, just add another drive and your pool gets bigger. The down side is that WHS only uses 1:1 mirroring for redundancy. This means that you would actually need
18TB worth of drives to hold 9TB worth of movies.
unRAID : Not as easy to set up as WHS, but not rocket science either. It's basically a very simple Linux build with a customized file system. unRAID takes drives of any size and can be expanded at will. Unlike WHS, it creates redundancy by using a single disk (the largest) for parity. This means that if you have 6 1.5TB drives for storage, you only need to add one more 1.5TB drive (instead of 6 more for WHS).
Standard RAID: You can arrange your drives in a standard RAID array under any OS you choose. RAID-5 (1 extra disk) would probably be ideal, or RAID-6 (2 extra disks) if you're feeling extra cautious. The down side is that RAID arrays are very picky. All disks in the array need to be the same size and preferably of the same make and model. Additional drives (of the same size) can be added to the array later, but only if your hardware supports it.
If you go for one of the first two options, you can use pretty much any hardware - even something old you have lying around. Anything P4-class or newer with at least 1GB of RAM should be fine. You may need an extra SATA controller card or two, but they're
quite cheap . Since you'll be building a raid with quite a few disks, the third option would require a hardware RAID card. They're
not cheap . Personally, I'd suggest you go with WHS or unRAID.
Any server is going to need a sizable case to house all your drives. I can offer some suggestions if you want, but it's not terribly important at this point. Right now you need to decide of you want to go with a server or not, and if so, what kind.
EDIT: There is one more option that I just remembered. It's the most expensive, but it's also the simplest. The
Drobo pro is a really smart NAS that holds up to 8 drives. It does pretty much the same thing as WHS or unRAID, but with zero configuration. Just stick drives in it and it figures it all out for you. It uses single-drive parity like unRAID, so you only lose one disk to redundancy. You wouldn't have much room for expansion later, but it still might be worth considering if you don't want to set up and maintain a dedicated server.