---Open Registry (regedit)
1> Close the game.
2> Go to the desktop.
3> Click on Start button (left side bottom)
4> Go to *RUN* (on winows7 it's the left bottom side when you opend *Start*)
5> Write *regedit* and press enter.

---Search the NP-Client
-> on 32 bit Computer / HKEY_LOCAL_MACHINE / SOFTWARE /GAMASOFT / NP-Client

-> on 64 bit Computer / HKEY_LOCAL_MACHINE\SOFTWARE\wow6432Node\GamaSoft\NP-Client

---Modify the decimals (Height & Width)
1> Double click on Height or-and Width
2> Now you get a window wich shows "Hexadecimal and Decimal"
3> Switch to "Decimal"
4> Change it to the wished size you want and click enter.