Vostro 1500 Dim Screen, What Should I replace?

It's a 4 year old laptop, actually a workhorse with sentimental value so I would like to replace the faulty part. I found a temporary software solution by turning up the brightness within the Nvidia CP but I would like to get it fixed.

I noticed over the last 2 years where the display was not as bright as it used to be. I also noticed that the upper right and left edges of the screen look somewhat brighter than the rest of the screen. So i'm leaning on a faulty display but i'm not totally sure until I get some input.

I compared my 1500 screen with my Vostro 1700 and I noticed the screen on my Vostro 1700 looks a little brighter and the color temp I would describe as COOL so the blues stand out more. My 1500 has a warmer color temp overall. I did replace the stock 8400m GS with a 8600m GT to play more games and no change in the brightness level.

So what do you guys think should be replaced.? :hi2:

 

It could also be your backlight showing it's age, given it's age, your display should be CCFL backlit and those do get slightly dimmer over time if I'm not mistaken.

 

Are you saying both need to be replaced or just the backlight?