Not sure about the SMP question, but ECCp, like most Distributed Computing projects, uses 100% of the FREE CPU cycles and gives them back if any other program needs them (about 99.9% of the time)...🙂
There will be a small lag for a few programs, but you'll never notice them on most....if not all! 🙂
Again, welcome and enjoy! 🙂
Next: Someone answer the SMP question! 😀