I'm just wondering but why would a Atom not work fine? I'll admit I have only been playing with the nes, snes emulators but I took a look and found project64 for the N64 and its requirements seem low enough:
- Pentium III 600 Mhz or better
- 128 Mb. RAM or more
- Fast video card with 16 Mb. Video RAM or more
- Windows 95/98/Me
- DirectX 6.0 (latest version of DirectX recommended
So really I'm not sure why it would not work. And then you can use something like Mamewah as a frontend that can switch in between the different emulators.