MBP Screen Not Working?

Okay, so for a few months now, almost every time I would move my Macbook Pro (I generally use it as a desktop, so move it verrry rarely) my screen would come on white and not show anything for an hour or so, (except a flicker or bleed of color here and there) when the image would suddenly flicker on back to normal. Now, it just stays mostly white, with lots of lines going up and down- the bit of 'color' in the lines does seem to match where windows should be on screen, but very generally, and it doesn't update in real-time, it 'refreshes' every so often... I attached a photo so you can see what I'm talking about.

I had my logic board replaced about a year ago now because of a faulty Nvidia 8600 chip (have a Santa Rosa MBP). I'm currently using an external monitor- which last time was exactly what I did when the chip started dying out.. and external display worked just fine then, despite the fact that the GPU couldn't drive the internal display anymore, so that's not a clear indicator that the GPU is fine... when I first started having this problem, I brought it to the Apple Store, and they ran the test on the GPU and said it was fine... but that was months back, so I don't know?

I'm thinking (hoping) this is a display cable issue and not a GPU issue- but does anyone have any ideas? Also, if it was the display cables at fault, how much would it cost to replace the display cables? (internal LCD -seems- to work fine, backlight, etc., I think it's the connection..)

**Also, as a side-note, since my internal LCD is no longer working, how can I boot into Windows XP (Boot Camp) on an external monitor? It seems not to 'plug and play' at all, unfortunately, and I obviously can't get to the display settings if I can't see anything on the LCD!**

 

Looks like it's another trip up to the Apple Store for me then *sigh* Love my MBP, but it's been having its' issues over the past year or so...

This is a June/July 2007 Macbook Pro, so any and all warranties have obviously expired- may or may not be able to afford to get it fixed anyhow, so it may become a desktop for me :/ I guess we'll see what they say at the Apple Store.

 

Just an update- my screen suddenly started working again... still not sure if it's LCD connection or GPU, either way plan on taking it to the Apple Store soon- I'll update with what happens..