Emulators are not upscalers, they are simply told to render the output at that image resolution. Dolphin has been worked on for a long time now, it used to be a Gamecube emulator project, and since Wii didn't really change the hardware architecture, emulating Wii games was only a matter of making the Wiimote work with PCs which has also been done for almost 2 years now. If you have a Wii, that's the best Wii and GC experience you'd have, don't bother with Dolphin since a lot of the rendering has artifacts and glitches and some games don't even work or simply run at crappy speeds.
As far as upscaling goes, I personally use a HD Box Pro which has component inputs to vga and it does anywhere from 480p-1200p( although it's more like 1080p view size with black bars on WS monitors.)
