This is the CPU and the motherboard that I suggest
Q6600 - $195
QCGO.com.au : Woolloongabba : Catalog: CPU : Intel : Intel : Q6600 QUAD CORE 2.4Ghz 8M CACHE1066 (G0 Stepping)
Motherboard - $105
QCGO.com.au : Woolloongabba : Catalog: Mainboard : Intel : MSI : P43-NEO-F Intel P43 Chipset 1600MHz DDR2 1066 PCI-E x16
or this motherboard - $100
QCGO.com.au : Woolloongabba : Catalog: Mainboard : Intel : Asus : P5K-SE-EPU S775 P35 FSB1600 DDR2 PCIEx16 SATA2 GbLAN AT
Q6600 - $195
QCGO.com.au : Woolloongabba : Catalog: CPU : Intel : Intel : Q6600 QUAD CORE 2.4Ghz 8M CACHE1066 (G0 Stepping)
Motherboard - $105
QCGO.com.au : Woolloongabba : Catalog: Mainboard : Intel : MSI : P43-NEO-F Intel P43 Chipset 1600MHz DDR2 1066 PCI-E x16
or this motherboard - $100
QCGO.com.au : Woolloongabba : Catalog: Mainboard : Intel : Asus : P5K-SE-EPU S775 P35 FSB1600 DDR2 PCIEx16 SATA2 GbLAN AT