Hi a friend of mine has a qnap459 he selling not sure how old says he upgraded to 2gb ram and come with 4 hard drives x1tb he is wanting 600 is this worth it for this also I only using for streaming movies 1080p multiple sources
The QNAP 459pro is a fairly high-end NAS box and probably overkill for your requirements. As others have said, something like the HP N40L Microserver (with the current cashback offer), or the Netgear readyNAS NV+ V2 at the current price would be much cheaper alternatives. Depending on your required amount/configuration of disk storage you're probably looking at around £300 - £350.
DAS is directly attached storage. As is you connect it directly to a host computer as opposed to a network. If you spend a bit more you can buy a NAS from Drobo. They're not the fastest machines out there but they do have advantages in terms of flexibility an ease of use.
A NAS will NOT stream to an ATV3 or iPad (I have a ReadyNAS, so I should know).
By comparison, the HP Proliant Microserver N40L WILL stream to the ATV and iPad.
If you don't like the HP Microserver idea, but would prefer something comparable with the Qnap 459, Netgear have substantially reduced the price of their ReadyNAS NV+ V2.
Specifically, it is much, much cheeper than the price that your friend wants for his Qnap 459 - that is, £160.
NetGear ReadyNAS NV+ V2 (4 Bay) - No Drives Included (RND4000-200EUS) - dabs.com
Netgear RND4000 ReadyNAS NV+ v2 4-bay (no disks) NAS.. | Ebuyer.com
Kikatek.com: (RND4000-200EUS) Netgear ReadyNAS RND4000 V2 NV 4-Bay Gigabit Des