Thank you all for your feedback. Very helpful. I bought a DVI cable retail just to see if it was worth ordering and I didn't see a difference. MAYBE a tiny bit on text clarity, but I can't even say for sure. Good to know you can buy the cables online for $10 though, I paid $55 retail for this thing and it's going back! I just checked to be sure I could return it before buying.
Maybe the improvement depends on the LCD model you have as well.