No problems in replying T-Man... I know all too well about real life pressures! So to counter answer the questions:-
1) Budget: If you can push out to that £1000 mark, there is no real need to break this, unless you go for that high(ish) end build I posted.
2) How fast you want it?: I did not ask this question correctly which has led to a mis-interpretation. My fault, so my apologies. The question was meant to be in relation to "How fast you actually want to get the computer in terms of... can you hold off for a while before you build or do you want it straight away?"
3) What peripherals?: Good to know that it is only the box needed. I would also recommend to see what you can salvage from an older build.
4) Multi-tasking or singlethreading?: You answered multi-tasking here, so I reckon that an AMD build would be better for you (more on this below).
5) How long do you want this build to last?: This means that you can mix the build up with some lower end parts with higher end, but swap them out at a later date for easy upgradeability (more on this below)
6) Will you be multi-screening?: If you do not want to multi-screen, then get a ard with 2GB onboard RAM as this will be plenty for most applications and games. It will even do dual screens fine. But if you add more than two screens, then you do want to be looking at the 4GB region. Also, 4GB onboard RAM will help to futureproof the card for games with larger textures, however, this will only futureproof for so long as new technologies appear.
7) Storage: I have an SHDD. Not as fast as SSD but it does the job for me. So the drives I suggested earlier should be fine for your needs.
The More Below Bit:-
I would recommend the AMD FX8370 if you are looking into multi-tasking anduse an ASUS M5A99FX PRO R2.0. This pair will cost about £250. It is what I currently use. Now for raw FPS and stupid levels of performance on single-threaded applications like games, it will not perform as well as an i7. However, they are more than adequate for gaming needs.
The beauty about this AMD chip is that it can get some insane levels of overclocking and currently holds he world record at something silly like 8GHz, but needed stupid amounts of cooling. The cores aren't as strong as Intels, but because there are more of them, it does mean that it can handle multiple applications better than Intels. The mobo will give you stable overclocks as well. If you do overclock, make sure you spend a bit on aftermarket cooling.
These two parts substituted for the i7 setup will work perfectly fine with the rest of the components I suggested in my previous post. Also, because they are less expensive than the i7 setup, it will also keep some cash back for the 3rd Quarter of 2016 when proper benchmarking can be done between Intel's Skylake architecture and AMD's ZEN architecture, allowing for a two part upgrade... although by this point and if you decide to go down this route, you might (?) be forced onto DDR4 RAM. If you did not want to upgrade straight away when the new architectures arrive, then this AMD build should easily last at least two years... but most likely more before you forced into an upgrade again.
IF you decide to go for the AMD setup, DO NOT go higher than the 8370, as you will need have to spend extra on cooling because of the higher TDP, which makes the chip run hotter. You also spend more if you select something higher than the 8370 and this is where AMD begins to use its "bang per buck" advantage over Intel.
Please note that I base this post on a lot of research and my own experiences, however, make sure you take note of what other people say as they will have different experiences to myself.
I hope you find this post useful, and good luck. If you post a part list, like I did with Mongoose, I will tell you what I THINK, you should change.
