It looks like the LCD to me, but it could also be the wiring coming loose or failing (and that's what I would check first.) You could check that it's not a GPU issue by plugging in an external monitor, but it really doesn't look like a typical GPU failure mode. A higher resolution screen might be a problem; your screen almost certainly uses LVDS, and different resolutions can have different numbers of signal pair wires. There is some overlap (i.e. 1280x800 and 1440x900 might use the same number of wires, while 1680x1050 might use more) but it's best to try to find the datasheets for your current LCD and whatever you would want to replace it with unless you also want to replace your video cabling. LCD pinout is fairly standardized at this point, but if you do get a different kind of screen you'd also do well to make sure you aren't connecting backlight power to a signal pin.
Finally, keep in mind that many of the ~$100 laptop "replacement" screens aren't real replacements and might be dimmer and/or have poorer color reproduction than you're used to. Good luck, and sorry about your screen - that's a great laptop when it's working properly.