Cracked LCD

I have an Inspiron 600m and have been having some major problems with the display.  I'm hoping somebody can answer a few questions for me, since the display seems to the weak link where laptops are concerned (i.e. tend to break and are incredibly expensive to fix).

Although the computer has not been dropped or kicked, I recently discovered what looks like a crack in the LCD.  The physical screen itself it not cracked, but I assume that the phsyical screen is just a piece of plastic and not the expensive component.  The crack is about two inches long and runs somewhat diagonally; There are dozens of randomly colored thin vertical lines running from the top to bottom of the screen for the width of the crack.  There are also a bunch of thick whtie lines running horizontally out from the crack toward the right of the screen.  Basically, I'm left with half a usable display.

My first question is: can cracks be caused by anything besides being dropped or struck?  The crack seems to the result of what looks like a rock chip in a windshield (although the plastic screen is not damaged at all).  Can a small crack result from, for example, the corner of a book being pressed into the computer in a full bag?  That's my only guess of what could have happened, and if so I wish I knew how fragile the backs of these displays are.  Light weight is nice, but I'd prefer a stronger case if it would avoid these extremely costly repairs.

However, since the display is cracked, and since I don't think Dell's limited warranty covers cracked LCDs in any situation, what's the best way to fix this problem besides buying a cheap monitor and using it as a really small, light CPU?  Will Dell send me a replacement display that I can install myself?  Do I need to replace the entire display, or can I just replace theh cracked LCD?  Also, will getting a replacement display affect my wireless setup at all?

Hope someone can help!  Thanks in advance...