Mobile barton 2400 and a NF2U will run about ~150$ and most oc to 2.4+. Either system will need good ram, pc3200 or 3500 for good oc results. On the other hand, bang-for-buck is different for different people. A P4C 2.8 is a strong chip, many oc quite nicely. If you don't plan to oc, an A64 3000@220$ is a viable option, great stock performance, especially in games. The radeon 9800 pro is prolly the bang-for-buck favorite vga card (~200$ atm).