Dreamcast would most likely not work on the N900 (due to low fps).

Pandora processor: OMAP3530 - 720 MHz ARM Cortex A8 + PowerVR SGX530 GPU + 520 MHz C64x+ DSP + ISP
N900 processor: OMAP3430 - 600 MHz ARM Cortex A8 + PowerVR SGX530 GPU + 430 MHz C64x+ DSP + ISP

However, psx should work on N900