From the specification you supplied you can install Mac OS X 10.5 Leopard.
The system requirements are:
Processor must be any Intel, PowerPC G5 or G4 (867 MHz and faster)
DVD drive (for installation of the operating system)
At least 512 MB of RAM (additional RAM (1 GB) is recommended for development purposes)
At least 9 GB of disk space available.
Hope this helps