^^^
What Jazz said.
I'm making the switch to uccnc also.
I have both mach3 and uccnc.
Now, where mach3 is concerned I have only had great successs with it using winXP. Had various glitches with win7. Mach is so old that I'd say it was designed for xp. Any other o.s. can be problematic and not many folk will have xp available.

I'm switching to uccnc mainly because I need more I/O and a higher kernel frequency, this is where Mach falls down for me as parallel has it's limitations. I've avoided using usb (recommended!!) and gone straight up to an ethernet controller instead. I'm still using mach with my uc300eth controller until I get fully familiar with uccnc.

Furthermore, I can hopefully save some power and run it off a laptop.