There are NOT two CPUs... its a P4 with hyperthreading, meaning it has two virtual processors. So the OS/BIOS/software thinks it is running on two CPUs, the performance is often better than a non-hyperthreaded P4, but not anything comparable to two actual CPUs. A HT P4 still has to share the same silicon with the 2 virtual CPUs. Note that hyperthreading seems to help a bit with WinXP performance, but with Win2k and possibly other OS/software it can damage performance.
Gameboy: actually that is an easy to intall and use super-cooler (compared to other solutions with that kind of cooling power, NOT for beginners ). That's why it says "-35 degrees C for the office". Meaning it isn't huge and massively dangerous and complicated like liquid nitrogen. Yet its cooling power is above most water-cooling kits, and you can sometimes continue using an existing case.
Still, the P4 at 4Ghz is undoubtedly the fastest single x86 CPU. Would it emulate Saturn full-speed? Probably not with all games, not with current stock emulators.