The best emulator, and the only one I run, is PocketGBA.
The newest version can be found here...
http://www.sunbug.net/products/emul/PocketGBA.html
*Note*
You cannot install the .cab...simply download the "direct installation".
It works great, if you have any problems let me know.
Then, if you need games for the emulator...just google for them....Romulation
The only trick is that you should probably turn off sound(it wont sound good) and that you probably need to set frame skip at around 3-5.
That is it...great emulator...plays a ton of newer games.
*Hint*
If you have problems loading games, make that you free up memory. It works best with no other software running.