Buying a computer based upon how much space it takes rather than by what it can do is perhaps the most mindless thing I can think of.
Unless of course you don't do any real work or have any real entertainment needs.
My last purchase was primarily based upon wanting to stream blu-ray quality audio and video from my computer to my audio/video system. The video part was much easier than the audio part.
Of course all of these things come in a small or at least medium-sized form factor now.
Maybe a nice coloring book would suffice for you...
I used to build my machines but I quit because the system prices made it tough to build something faster and stay within my budget. I don't buy the latest and best parts because they will be knocked from that position in short order. I tend to buy when I need/want something new and buy at the the price/performance part of the curve just below the steep price rise. My last machine was a Dell Studio XPS 8300 for $599. I have grown lazy.
The "best CPU" answer really depends on the job that it is going to do. What application will you be running and where will it bottleneck. Most routine tasks are single threaded and beyond a certain point, cores will idle down and not be used. There is a certain amount of "religion" involved in the decision. I have no experience with any of the AMD CPU so I cannot offer any recommendations for/against there. There are a number of sites that discuss the gory details and share experiences.
I have been pleased with the Quad Core Sandy Bridge. I don't play video games but I did get a 35in 1920x1080 monitor (for my eyes and Netflix).
ark.intel.com will let you compare CPU side by side and what features match and are different.
Wikipedia has some good table on Intel and I expect AMD.
The most common bottleneck is memory: speed and size. Slower memory takes more cycles to get data to/from the CPU. The CPU waits for data. When the memory nears being full, it will start tossing some memory pages to disk. Putting the page to disk and getting it back is msec instead of nsec. 1,000x slower. I target 8gb of memory. 6gb would probably work but the system had 4gb and I got a pair of 2gb.
Pay special attention to the memory.
Add up the watts you will be expecting to burn so you do not have to upgrade the power supply when you select your GPU board. Many require an oversized supply.
Ah, pricing. I don't know for sure but I would think it has something to do with Intel wafer starts on each geometry. They have a fixed 45nm capacity and will not be expanding it. They would more likely be adding 32nm or smaller capacity if any.
It does encourage migration. 8-)
I have a Yorkfield 8200 system and a Sandy Bridge 2600 at home. When I load them down with all the cores (and Sandy threads) cranking, the Yorkfield runs much hotter and requires more cooling than the Sandy Bridge. The Yorkfield is a 45nm part. You might gather running temperature data on the CPU.
"Desktop GPU revenue declined in the typical seasonal fashion, said Burns, while notebook GPU revenue rose as the company gained market share with sales of machines based on Intel’s (INTC) “Sandy Bridge” processors."
Barely beat estimates & their forecast is barely higher than the mean estimate. Most of the gain came from taking GPU share from AMD. Traders are having their way with this stock once again...