The 1905FP, like most Dell Flat Panels, uses the 100mm VESA wall mounting standard:

 

 

 

I would highly suggest you use that instead of balancing it against another object.  Sudden drops can cause the connection between the logic board and LCD panel to break, which would cause lines or no video on the screen.  This is not covered under your warranty if Dell determined it was damage.

 

So no it would not be harmful, but I'd spend the extra $$$ to get a real stand for it.  as long as air can move above and below the panel, it can cool itself, but you don't want to damage it.

 

Here is an example of a cheap wall mount:

 

http://wwww.electrogalaxy.com/index.html?object=vptax2wl02s