Iwould choose ASrock 4CoreDual-Sata2 with Via PT880 Ultra if i was low in budget. It supports quadcore, AGP graphic card, DDR and DRR2 ram, PCI express, Raid and all other stuff that you'll need.
I would choose Gigabyte DS3R with P965 chipset for midrange because it's affordable and overclocks quite good.
I would choose Asus P5B Deluxe or Asus P5K Delux for high end because it yeilds high FSB, looks good, the brand is well known, allows you to show off, and support future processors. ( only Asus P5K Deluxe with P35 chipset officially supports the future processors)