I have a four and a half year old HP Pavillion dv4 laptop. Today, I saw a thin 1px red horizontal line on the near top of my laptop screen. The line sometime changes to light blue. I tried connecting an external monitor and found that the problem is with the hardware. After a while display started to flicker a bit.
The graphics works fine and drivers are updated too. I know that this is a problem with the display(hardware).

I am thinking of getting rid of the display as I don't think that taking my laptop to HP support would be of any help. So is it possible to connect an external display after removing the laptop's default display?

I am thinking of getting a monitor which I would like to connect to my laptop after I remove the display component. What are the problems that I might face? Also my laptop has Nvida GeForce 9200 GM card and the resolution of my laptop was 1280x800. Now should I get an HD monitor? Will my graphics support an HD display?

If you have uninstalled the old drivers, reinstalled, then the only thing else it could be, is the Inverter or LCD screen. Flickering is usually a sign of the Inverter going bad.

You can use this site for a guideline on pricing http://www.sparepartswarehouse.com/HP,Laptop,Parts.aspx I have purchased parts through them in the past, and never had any issues.