Mac is an all in one..
If you want seperate components.. BUY seperate components.. if you want all in one, buy an iMac.. don't try to make one into the other..
HOWEVER, that having been said, I did read the tech docs released by Apple, and it looks like (and logically makes sense) that inside the Mac itself, there is a standard connecter with standard signals passed to the nVidia grfx chip. . this means that, of course, the LCD panel can be hacked to work on other systems, but you have to know what you're doing (ie, you need charts showing the lines going into the connectors on both sides and would have to hack up the LCD panel to give it a longer cable wired correctly--not to mention having to probably rig up a seperate power supply for the LCD panel as on any normal tower there would not be power signals coming out of the VGA port, now of course, if it's going to be hooked into an Apple tower, then there are power signals out on the video port..)..AND THEN.. you have to find a way to hold the screen up unless you want to use the iMac as an LCD panel hanger.. probably not worth the effort though...