I have been mining ZEC on my desktop for several months, using Ubuntu 12.04 and a midrange Radeon graphics card. My rig mines about 0.01 ZEC a day, or about US$1 a day at today's rates. CPU mining would probably produce less, and a better graphics card could produce more.
The best results you get when you have good CPU and graphics card.
The ideal solution is to mine a coin with GPU and other coin CPU only with the CPU. However is it a bit messy to have 2 programmes, and the CPU miner load should be ajusted in order to not disturb GPU mining.