DeSmuME is a freeware emulator for the Nintendo DS created by YopYop156. DeSmuME is also known as YopYop DS is written in C++ for Microsoft Windows and can play Nintendo DS homebrew and commercial nds roms. The emulator its self is in French (with user translations to English and other languages). But even French version of DeSmuME is easy to navigate through menus as it has a similar users interface to DSemu. It supports many homebrew nds rom demoes as well as a handful of Wireless Multiboot demo nds roms. DeSmuME is also able to emulate some of the commercial nds rom titles which other DS Emulators like iDeaS and Dualis aren't capable of doing so.
THE8THARK I have used DeSmuME 0.9.4 and it works with many roms. Mind you thay are too slow to be playable on the intel C2D imac I have at the moment. But when I tried the same roms on 0.9.5 the app opened up ok (with a very ugly windoes-esk menu) and I loaded up some roms and they either simply do not work at all or crash the application.
It seems 0.9.5 is a broken release that needs fixing. If you can get the roms working on 0.9.4 stick with that for the time being. (Version 0.9.5)