The following are the hardware requirements:

1 GHz processor

1GB RAM (minimum)
The number of Outlook contacts that the system displays is limited by the available RAM on the computer on which the plug-in  is running. Loading too many contacts with insufficient RAM can result in the degradation of performance on the machine.

1 GB+ free disk space for 32-bit operating system or 2GB+ free disk space for 64-bit operating system.