Don't be surprised that DS Emulators are not the best way to play roms. You can get much better compatibility and perfect speed with 
What started out as a GBA development tool and emulator for GBA roms is now one of the best and most compatible Nintendo DS emulators.
WinDSPRO is not an emulator, but rather a nice and easy installer for all the best emulators and their add-on plugins like NO$Zoomer, NO$GBA 2X, VBA Link, VBA-M, iDeaS, DeSmuME
Even the cheapest DS/DSi Flash card that these days costs only $10 USD will work better than the best emulator so there is no reason not to buy one of these blank carts for playing NDS roms on DS.DualiS DS Emulator
What is DualiS?
It is a PC-based Nintendo DS emulator, which uses plug-ins to function. It works with Win 32 or x86 computers, and it is coded in C++ and x86 assembly languages.
Recent Developments
Unfortunately, the makers had their final release on the 27th of May, year 2007. The latest improvement is on the 256 color palettes, which enable 256 colors texture display. Recent versions, which were released on or before May 3, 2006, have been severely bugged. For example, opening a ROM through the File menu caused the program to crash. The May 2007 release solved these issues. The complete emulator installer is only 277 kb small.
However, due to some legal issues, the Dualis project was stopped. The developers did not finish the D3D renderer, which was intended to handle 3D mapping command. Due to this limitation, the program can only partially emulate some commercial games and none is fully playable. It is recommended to operate the emulator on at least a Pentium 4 PC, with a minimum of 2 GHz processor.
Installing and Running the Emulator
You can download the DualiS Emulator Installer from our website. In case of runtime problem, you can download the support files from the same section. Extract the RAR file to a folder; then, double click the installer executable. Choose the destination folder, if you want to change the default setting at C -> Program Files -> .
Then, choose a graphics renderer. Generally, the video plug-ins of the emulator work with all commercial video cards. However, try to play with the settings since some renderers work better with specific video cards.
Now, you can finally browse and run a DS ROM file.
DualiS Compatible DS ROMs and Programs
Unfortunately, due to the classified legal issues, the makers of DualiS stopped developing the software — even before it could fully play commercial titles / nds rom games.
Generally, the games playable in the emulator are homebrewed - made by the programmers themselves, supporters, consumers and fans. Hence, the emulator did not reach its full potential in terms of display, audio, programming and bug fixes. The dual screen system, which was originally intended to imitate the screen-tactile pad combo of the real NDS, was never completed. In most of the games, the other screen is black with an error notification. Nevertheless, the software perfectly worked as a gallery viewer of images and DS homebrew game & apps.
Since all playable software does not include commercial games, you can’t expect to play the real Sonic, Pikachu or Mario on your PC screen with DualiS emulator. Anyway, the programming is still underdeveloped to fully play the official games. If you are still interested with hacked and custom ROMs, you can visit their forums for downloading. The games do no look impressively rendered but, in fairness to the programmers, they have created a lot of quality mini games.
The games and software for Dualis include Table Hockey, dozens of modified Super Mario 2, a noteworthy piano and music application, calculator, Tetris, puzzles and several mini games. Many ROMs are simply intended for technology demo, like polygon viewers, color and sound testers.