Customers that buy a qualifying X-NAS product (either the X5520 with 8TB or 16TB or the X1600 Network Storage system or Gateway) with one of three HP ProLiant DL360 G7 server SKUs will get a cashback of up to £1,399 until the end of August 2012.
The best option would obviously be to buy the cheapest X-NAS product, which is the barebone StorageWorks X1600 G2 network storage system at £3,545. The StorageWorks X1600 is built on a ProLiant DL380 G6 server chassis with a quad-core Intel Xeon E5520 processor clocked at 2.26GHz and 8MB L3 cache, 6GB of ECC DDR3 RAM, 25 2.5in hot-swappable bays (up to 24TB internal storage), a Gigabit Etherenet port, a 750W PSU.
If you coupled that with the most expensive ProLiant DL360 G7 server, which is an SMP capable model with a single quad-core, 2.4GHz Intel Xeon E5620 processor, three 2GB DIMMS (6GB of RAM), three year next business day warranty, a DVD writer, a 750W PSU, hot plug SFF diskless and a Smart Array P410i/512+BBWC storage controller. This server would cost £1,399, but you'd get that outlay back via the cashback scheme.
Note that the prices do not include VAT and the offer is valid for UK customers only from selected retailers.