[quote name='Achmat'](will games only work on the new dsi?)[/QUOTE]
Yes. Aside for the DSiWare games (of which the Art Style series is the only thing worth looking at so far) there are a few incoming exclusives. There's not a lot yet, and some games will work on both with enhanced features for the DSi--like Link's Awakening DX did for the GBC.
To be fair, though, you miss on a few games on the DSi as well. Anything that requires the GBA/accessory slot won't play on it.
I'd say there's no compelling reasons yet to skip a good DS Lite deal in favor of a DSi.