Quad Core with Lower CLock vs Dual Core with Higher?

The I7 Dual Core will do just fine.

If however, you are running more or doing more with Final Cut Pro, the i7 Quad will be more efficient because of the Quad Core Design.

It might sound like the i7 Dual is faster than the i7 Quad.

In day to day usage, browsing the net, watch dvd's and some other apps, no difference will be noticed.

Once you get into heavy usage, the Quad will be faster.

2.0 GHz x 4 cores = max 8.0 GHz processing

2.8 GHz x 2 cores = max 5.6 GHz processing

Plus the quad-code has hyper-threading which can double that 8.0 GHz processing.

Note that these numbers are very simple calculations of theoretical limits. In real life not all applications fully use all threads on all cores. But the upper limits of the quad-core are still higher than the dual-core.

Not to mention the minor speed increases of the quad-core due to internal cache speeds and other differences.

If it were up to me, it will boil down to:

The 2.2 Quad i7 with 15 Inch for $1349

or

The new 2.9 Dual Core i7 with 13 Inch for $1199.

If screen size is not a problem, invest the money on the 13 Inch 2.9 with 8GB of RAM.

Yes it might perform slower than the Quad but it's a new model and you will get compensated by the faster RAM (1600MHz vs 1333Mhz) and newer Ivy Bridge Processor.

The 15 Inch however, has it's own dedicated graphics controller.

I would still choose the newer 13 Inch.

Did I confused you even more?

I have the 2.0 quad core (refurbished, purchased last July), with anti-glare and hi-res. Th extra windows my 1680x1050 can show and the lack of screen glare is a good thing, in my opinion.

If you can find a refubished with hi-res and anti-glare, I would put the extra money there instead of the extra 0.2 GHz.

15" with anti glare if you can get it would be my choice.

Ciao.