First, install the latest version of PRTG on the new computer to keep downtime at a minimum.
In order to move a PRTG Traffic Grapher installation to the new PC we recommend to first make a copy of your current installation into a new folder. To do this please use the "File -> Save As..." menu entry, create a new folder (preferably on a shared network drive), choose a new filename, and then click "OK" to save the data. This will create a .PRTG configuration file with the current data and also copy all relevant historic data files into a subfolder of the selected folder.
Afterwards, copy the new folder with all subfolders to the new machine. Now start PRTG Traffic Grapher on the new machine, select the "File -> Open" menu item and select the PRTG file that you just copied on the new machine. This will restore the sensor configuration, as well as the historic data available.
Note: Because the data cache must be recomputed, the initial startup can take some time (even hours for large installations, see below).
The final step is to open the "Extras|Options" dialog and review/set all (!) settings.
Please note that your old configuration data is not touched during this process and the previous installation is still active. After checking that the new installation works fine you should halt monitoring on the old PC to keep network load low. Later eventually delete the old data manually and deinstall PRTG Traffic Grapher. Make sure the service has also been uninstalled. Otherwise it would start up after rebooting your system.
Some Notes:
(common documents)\PRTG Traffic Grapher\prtg traffic grapher.ini"
For more information about how PRTG stores its data please see www.paessler.com/support/kb/questions/25