I don't remember that Wifi ever worked in PearPC setups. such hardware was never supported. Also, the sound emulation got stuck in "goede voornemens" (good intentions). Its also good you mention the reason why you want to run Pearpc, so now I can at least recommend you don't try it. PearPC works, but it is very slow and has at lot of problems.
If you want to run Mac OSX on top of windows, why not look at the VMware/OSX solutions? They allow you to run with the latest Snow Leopard version and are a lot quicker.