MacOS Leopard doesn't include anything new to allow you to run Windows apps at the same time as MacOS.
It does include a new thing called "BootCamp" which allows you to create a Windows partition on the harddrive and install Windows on to that partition and then boot into EITHER MacOS OR Windows. (but not both at the same time)
There is a thing called "Parallels software" which is a kind of Windows Emulator ( a virtual machine) that allows you to run windows and therefore windows software on MacOS. Paralles (and a few other virtual machines like that) have been around for years.
I'm not sure if it's DNC software what you're looking for but if it is then we (easydnc.com) have just released a version of our dnc software which runs native on MacOS http://www.macdnc.com It's a universal binary so runs on new Intel Macs as well as Older PPC Macs
As I said, I'm not sure if it's DNC software what you're looking for but, for now anyway, that software is free of charge so it won't cost you anything to try it.