this is a mono cpu, with a ram of 768 mega, 1 internal hard disk up to 80 giga, and a superdrive from pioneer. it is the best choice for every system who needs pci port (and not x or express), for example some sound cards from motu (pci 324, 424 with their extensions), many protools configurations, even the first protools hd system from digidesign, or the digi 001, etc... i add a iyama 17" crt display, wich is very good for video editing, a little bit small maybe, but with a good impact. the os x is tiger 10.4.8, but you are able to change it with an older system anyway.