It is possible to achieve good overclocking results with motherboards costing slightly above $100. However, we decided to go with a decent mainstream model, because spending roughly $150 will give you a powerful product that is only inferior to high-end models when it comes to providing large amounts of interfaces and sophisticated cooling options for hardcore overclocking. We believe it makes sense to purchase a decent motherboard, so it can support the 45 nm processor generation based on the Penryn core. Let's not forget that there might be another low-cost processor in the 45 nm future that could also be greatly overclockable.
Our choice was a P35-DS3P by Gigabyte, which we purchased for approximately $160; we plan to use it in a desktop PC after this project is finished. If you don't want to spend that much, you could have a look at the P35-DS3, which would have sufficed as well. Going up the portfolio, the DS3R is the first model to support eight SATA/300 ports with RAID. The DS3P also comes with Firewire and a secondary PCI Express x16 slot for dual graphics setups. (However, the second slot is only PCIe x4 only.) All DS3 motherboards come with a six-phase voltage regulator and comprehensive overclocking options. The DS4 has more sophisticated component cooling than the DS3 family.
While we played around with the Pentium Dual Core E2160 to find reasonable overclocking settings, we discovered a pretty interesting detail. If you do not change the CPU voltage when overclocking and set this item to "auto", the P35-DS3P will automatically increase the CPU voltage, which helped to run the processor at up 3 GHz without manual fine-tuning.