Hey, why would you choose a DDR 400? Why not DDR 2? DDR2 is gaining popularity nowadays..and it is becoming cheaper too..
Ive seen an ASUS mobo there.. it's priced at $300+ is it cheap enough for u? It has all the support for the latest processor.. I suggest an Intel Core 2 Duo (Conroe) E6600 for u.. It's priced at around $300 also....Your memory, U can go DDR2 667 or 800... I dont know the pricing..
Here's the product:Asus P5W DH-Deluxe WiFi Intel Socket 775 ATX Motherboard