AMD vs IntelWatch
AMD is cheaper, but Intel seems to be slightly better in some areas except it's really expensive...
That being said, I have and AMD A10 and it's excellent.
I bought my first AMD chip when I didn't have a huge amount of money so I went with the Phenom 2 and it was a great chip. I had good performance for the price and I had the extra benefit of being able to easily overclock the processor with ease to push even more for my price. AMD usually offer their chips with a higher clock speed than most Intel chips, as well as more cache.
Intel will most likely always dominate and if you can afford to, stick with Intel. The performance in multi threaded applications will blow most AMD chips out of the water. Intel has always generally had a good architecture whereas AMD has struggled over the years. The bulldozer was a bit of a let down where as the piledriver felt a lot better for what I needed IMO.
I own a i5 on my laptop and a 3870k on my desktop. In single applications, my 3870k does fantastic and the extra benefit of the built in HD6650 graphics meaning I can even do some low graphic gaming without buying a card. The chip does run hot and requires memory from the RAM because the graphics chipset has no memory.
If if you don't have the money but want to game and do things without much delay, go with AMD. A decent £20 heat sink will compensate for the larger TDP on the AMD architecture and you can overclock most AMD chips without having to worry about understanding clock voltages.
Intel if price isn't a concern and the unlocked chips can be overclocked.
Two is is quite ample but the more process intensive applications like high quality games, video editing software or 3d modelling for example, more cores with a higher clock speed would become a necessity.
TL;DR two cores is ample.