Did a search on newegg for Intel LGA775 motherboards with at one AGP slot and one PCIe x16 slot and got nothing. I'd just pick up a new graphics card.
Motherboard:
Asus P5Q-E LGA775 4x240 pin DDR2 1200 2xPCIe 2.0 x16
$139.99
http://www.newegg.com/Product/Produc...82E16813131296
CPU:
Intel Core 2 Duo E7400 2.8GHz
$119.99
http://www.newegg.com/Product/Produc...82E16819115206
RAM:
G.Skill 4GB (2x2GB) DDR2 1066 cas 6
$47.99
http://www.newegg.com/Product/Produc...82E16820231226
Graphics card:
Sapphire Radeon HD4670 512MB
$79.99
http://www.newegg.com/Product/Produc...82E16814102818
Total: $387.96