Cadence makes EDA software.
I have not run any sesign software on an Atom platform but I have run it on slow laptops and the experience is not good. I would not recommend this.
Cadence software works fine. I've tested and installed SPB16.2 using a 1.2-1.8GHz Atom processor. If you want it to work well, I recommend more memory for windows vista or more hd swap space using linux.