I still don't think it will be enough. More ram and at least a 7950/670 I would imagine, and I still don't think that will play things comfortably depending on what framerates you expect.
I play mostly at 6048x1080 at the moment but I don't expect to be doing that with next gen console ports. I will even be suprised if my machine is capable of holding next gen console ports to 60fps at 1080p, but until they actually launch we won't really know.
Either way paying more for a pc is fine as its a much more complete experience for me. I always used to buy at least one console, this is the first time I'm really not interested in them at all.
I would say for comparable / better performance in all PS4 games at the same resolution (1080p) with anti aliasing you are probably right....
I would say the following PC would be actually as good or better in every PS4 game in real world usage....
Nvidia GTX660 TI / GTX 670
Intel i5 2500k
8Gb Ram
And that is going to cost more like £800 without a monitor... But I am pretty sure that would beat the PS4 graphics in most games. As had been mentioned before and quoted by some game developers you need a PC about twice as powerfull for better performance in all games. Sometimes you need even more than that if it is a bad port for example GTA4 you need a 4GHZ+ i5/i7 just to run it well on PC.