For 800 dollars this will be perfect for anything you need. AMD and Intel are identical in performance. AMD is cheaper for one reason, that is advertising. How many AMD commercials do you see? I have not seen one yet and I do enjoy a fair amount of television series'. Intel however seems to have one or two I see every week. Commercials are not cheap to put on TV and this is a big marketing scheme for Intel to hike up the price and sell more product. As someone said, AMD run's hotter, so you will have to spend money on a fairly good cooler for it. I bought mine from PCUSA.com and it cost $650 three years ago, it was a Quad Core AMD 2.8 or 2.9GHz Phenom II with a 9500 GT NVIDIA card, 6 GB of Ram and then I bought the worst fan available on the site for money reasons, the site only has good products but it spins at about 6500 RPM if I am playing any graphic intense game and that is about equivalent to a jet engine when I am trying to hear sound without waking up the family at night. But overall I would much more prefer to spend 300 dollars on a fan and spend 600 dollars less on an equivalent processor. Those just being taken as numbers as a fan should not be that expensive, yet Intel does host up their product fairly high.
For computer it is not a straight line multiplication for GHz but I believe you listed it at 3.5 GHz six core. Don't care what amount of GHz the I5 is, I believe I5's only went up to quad core, which means it will never be able to keep up with 6 cores. The i7 laptop I have now is a dual core 3.9 GHz, it runs a little slower than my quad core AMD computer. The comparison is estimated at about 3.9 x 2 being 7.8 to 2.8 x 4 being 9.2. The intel cores can hold more information in each one meaning they don't have to switch between cores as frequently as a multiple core, but it will not make up for the extra GHz. If you want more performance you want more Cores. Only when they are equal cores do you really have to worry about the GHz.