In retrospect, most of these builds aren't fair because I utilize combos and you don't. On the flipside, if you were building an entire system from scratch and used Newegg to any degree, you have to at least try and see if any are useful. Me, I'm a filthy, filthy combo degenerate.
That said, I made some assumptions about this price point:
* CPU Overclocking is very accessible and frankly expected at this price point
* Crossfire/SLI is out of the question, as it requires too much of our budget for a worthwhile multi-GPU/PSU/Motherboard setup
* Given the above, we want a mid-range [500-600W] but rock-solid PSU so we can throw any CPU+single-card/single-core GPU at it easily
* DDR3 is still out of reach budget-wise
Sub-$750 build, AMD:
$254
- XFX Radeon HD4870 1GB + Phenom II X3 720
$140
- Gigabyte GA-MA785G-UD3H + 4GB G.Skill DDR2-1066
$110
- Corsair 550W PSU + Samsung SATA DVD-RW
$90
- Cooler Master 690 + CM Hyper-212 120mm CPU cooler
$70
- Western Digital 6400AAKS
$9
- Arctic Silver 5 OEM
Subtotal: $673 (plenty of leeway since we're abusing combos here)
Sub-$750 build, Intel:
$160
- XFX GTX 260 Core 216 + BATMAN
$120
- Intel Core 2 Duo E7500
$110
- Corsair 550W PSU + Samsung SATA DVD-RW
$90
- Cooler Master 690 + CM Hyper-212 120mm CPU cooler
$80
- Gigabyte GA-EP43-UD3L
$70
- Western Digital 6400AAKS
$60
- 4GB G.Skill DDR2-1066
$9
- Arctic Silver 5 OEM
Subtotal: $699 (It has BATMAN, which clearly makes it better than the AMD build)
Thoughts:
* The Cooler Master 690 case was chosen due to its general appeal and combo with the Hyper 212 cooler, which is especially appealing given its price-to-performance ratio.
* LGA 775 is a dead socket blah blah blah but
the E7500 matches up fairly well with the X3 720 given their equal sale prices, and two cores OC'd to the 3.4-3.6 mark won't be obsolete anytime soon.
* I opted to keep the motherboard simple by picking a P43 board; it has pretty much everything its P45 version has except onboard RAID.