Not enough power (electrical problem) Please help.

Hello everyone i have an 03 harley davidson f-150 and i am having what appears to be a shortage of power. I installed an xm radio, fm modulator, a small 6" lcd screen, and an old desktop computer which is running off of a power interverter. All that seems to be dropping the voltage to below acceptable levels because the computer starts having problems running and the lcd screen gets interference. I was wondering if anyone knew of a way to overcome this? Would a higher quality battery fix it? Or do i have to run 2 batteries, or even a better alternator? Thanks in advance for any help!

You need a secondary power source battery - these are placed in the back and are deep cycle that run a long time - ask your local auto sound store about them. They are a couple of different manufac turers.