For the N900, I'd fix the screen bandwidth issues and include a 3D accelerator so we could get nice, smooth effects in the OS. I'd also upgrade the CPU and RAM, but much of this could be accomplished with a new SoC. (The OMAP3530 looks really nice, especially with it's power saving automatic idle function.) Other than that, I'd keep that same general design as the N810. (Though with dual SD slots like in the N800.) On a side note, it would be nice if Nokia offered a USB On-the-Go cable with the device.