would the 72hour backup thing be worth it in case of power cut? Would it save the hdds from losing data?
The battery can help prevent data loss during a power outage, so long as the data that was being written all fit into the card's cache.
If you don't have a decent UPS already (stay away from units with stepped inverters as they can actually damage your MP's PSU), then that is even more important.
So is a proper backup solution (no matter what the storage system is, nothing is stable enough that will allow you to skip a backup system.
4x 2TB hdds - using 2x3 as a RAID and 1 drive for normal stuff.
Would any old HDD matching the spec of '7200-rpm Serial ATA 3Gb/s' do? (ie -
http://www.amazon.co.uk/Seagate-Bar...KCLS/ref=sr_1_1?ie=UTF8&qid=1313258701&sr=8-1
If the RAID is attached to the SATA ports in the system, any SATA drive will do.
But if you go to a RAID card, then no. For this type of implementation, you must run enterprise disks in order to make sure the array is stable (consumer disks, such as the Barracuda won't be, and could cost you your data).
Graphics - Could I update the graphics card easily?
Yes (presuming you're only going to use OS X, make sure it's supported).
Put another 'ATI Radeon HD 5770 1GB' in OR 'ATI Radeon HD 5870 1GB' (which is better 2x 5770 or 1x5870 - could you use 2x 5870? )
OS X doesn't work with either SLI or Crossfire, so additional cards are only good for running additional monitors.
As per what unit's to use, the 5870 is probably a better choice for a single card.
Now if you are after a second card for additional monitors, and decide on a 2nd 5870, then you'd need to run an additional PSU in order to power it (jump the green and black wires in the CPU connector to turn the additional PSU ON). Not pretty, but it will work.
Not so big a deal, how easy to stick another superdrive in?
Easy. Remove the optical drive carrier, add the disk, make sure the connectors are in the right place, re-install the carrier, and you're done.
Also, currently have a mac book pro - MDP - DVI adapter to my HP monitor - im guessing just connect this to the MDP on the Mac Pro?
With existing GPU's for the MP, Yes.
ALso, suggested places to buy in UK - I perhaps would use crucial for memory, amazon uk for hdds, and where for the graphics card? How easy is it to upgrade the mac pro?
Perhaps
scan.co.uk...