The DSi can play GBA back-ups. The 16MB RAM is more than enough as far as that goes. But the main thing is, even though loosing GBA support, the DSi did NOT drop the ARM7TDMI processor, which is the same processor used in the GBA. True, the GBA had a co processor, the Zilog Z80. It is only an 8-bit processor. The DSi's main is the ARM9TDMI, another 32-bit processor. Now, one could hack the DSi, and add in GBA compatability, using the ARM7 as the main processor, and the ARM9 to replace the lower, 8-bit processor. This is highly possible, but would be highly difficult to do as well. Viva la' ADVANCE! Edit: As well, the DSi has 256MB internal flash memory, which can be used in virtually the same way as page file memory. For larger games, cutting down a lil' on the sound quality and running it at a lower resolution with minimum distortion would make the frame rate nearly perfect. Remember, no type of emulation is perfect, but possibilities are endless.