The 845PE was supposed to be Intel's mainstream desktop DDR chipset, although the e7205 (the Granite Bay), and now the 865 and 875, have stolen much of its thunder with dual-channel DDR. However, it remains an appealing platform thanks to Hyper-Threading support, official DDR333 support and the ICH4 Southbridge, which includes the USB 2.0 controller. While there’s also an enhanced AC’97 controller, most manufacturers choose to use separate six-channel audio.

One of the main limitations of the 845PE is its support for AGP 4x only. The other limitation is that the chipset supports a maximum of 2GB of memory, and only two double-sided DDR DIMMs can be used because banks two and three are shared between two sockets.

Essentially, the 845GE is identical to the 845PE but with integrated Intel Extreme Graphics. 

Addition of a CNR slot allows for cheaper implementation of peripherals such as: LAN; DSL; USB; wireless technology; audio and modems, although there aren't a great deal of available CNR peripherals floating around, so it's value is pretty nominal.
In performance terms, the lack of dual-channel DDR lets the 845 down, and only it's generally lower price would make us recommend it over the 865 or 875.