Problems with computer assigning a port to arduino mega

Hi every one as you will see from my question I am a newbie. I am at a loss as to why after installing arduino software 1.6.9 my laptop is able to recognize an arduino uno R3 original not a clone and it assign a port with no issues. When I try to do the same with my Arduinomega which has the ramps1.4 shield as installed by vicious1 it does not assign a port but it continues to ask for a serial driver? The ramps board is working perfectly with the full graphic control screen (only the screen is unable to be contrast adjusted) “side issue” I am able to move the motors with no problem using the Marling contols via the screen inter phase with no issues.?? any help Please!

Mac or PC? Mac need different settings, found on the ramps assembly page.

PC XP operating

It is a driver issue with XP. There is a driver that works but I don’t have experience with it. XP is pretty old now.

HI I have found several ways of solving this issue of the missing XP driver for arduino mega 2560 r3
1)How to install Chinese Arduino Mega 2560 Drivers. quick downloan then lauch set up
2)Arduino Forum Using arduino=>Installation & Troubleshooting=>Topic started by:d0m3on jan 10 2012 posted jan 10 2012 9:38 pm
3) I chose the firt

I discovered a you tube video explaining the same it is in Spanish wich i am fluent on this is the link

Thanks for the help vicious1