The following is the hardware and software requirements for Parallels Desktop 4 for Windows & Linux.

Hardware Requirements

Platform:
x86 and x64 platforms with Intel VT-x or AMD-V hardware virtualization support is a prerequisite.

CPU:
1.5 GHz or higher processor.

Memory:
2 GB of RAM (4 GB or higher is recommended).

Hard disk space:
150 MB of free disk space for Parallels software installation
30 GB of free disk space for each virtual machine. Size is dependent on programs and data that reside in each virtual machine.

Network:
Ethernet network adapter
Valid IP address

Note: The actual number of virtual machines you can run on a host computer and their performance depend on the resources they require. In general, the more resources your host computer has, the more virtual machines you can run and the higher is the performance of each virtual machine.