but for budget quads, I'd go with the AMD Phenom II 965 Black AM3, 125 watt quad. their $180 USD vs $500 for the Core i7 quad.
Motherboards? I've been running Gigabyte AM2+ and AM3 boards the last year or so, switching from MSI boards. So far their great.
Memory..I've used Patriot and OCZ memory also without any problems, but I don't overclock the processor.
Video? ATI right now is the best card built for the price. I used to be 100% nVidia, but ATI has gotten their drivers under tighter control than previously and they work great.
If the board handles 16 GB and you can afford the price, get 16 GB. Last year during the summer memory was cheap. Around $90.00 USD for 8 GB so I got 16. Can't say enough about what 16 GB of memory does for system performance. Windows 7 64 with 16 GB of memory and an ATI Radeon 4890 which is 256 bit memory interface. Would n't buy a video card that's 128 bit interface. The 256 bit give far more performance, in my opinion than any nVidia 9 or GTS 250 series cards.