Favorite Surveillance Software?

I bought a cheap LaView analog home surveillance system last year. It came with 6 analog cameras and a 1TB 8ch DVR. The LaView software sucks pretty bad, so I've been using Security Spy on my iMac (and do remote viewing with tinycam Pro). The biggest problem with this setup is that the Security Spy software uses 40%+ of my CPU, which makes the iMac run hot and become unusable when running other powerful apps.

So can someone recommend software to run on my iMac? Cost is a factor, however I would be willing to buy a low end PC to be designated for home surveillance. I'd like to receive motion notifications on my android and iOS devices, as well as figure out a way to have my live camera feeds viewable throughout my home.

Any input appreciated. Thanks.