I got a Deore 9 speed shifter and a LX Derailleur. I need to change the cables already since it's all untangled and such. I was looking on Ebay and I found some XTR cables for a good price. Is there a differences between the ordinary and XTR cables? I'm assuming it would fit the shifter and derailleur without a problem no doubt. Or am I wrong?
Yes they will fit. and we don't know what your bike came with so we can't compare to ordinary as you called them but most cables will feel the same to most riders. The difference is minimal to say the least.
I always use the Jagwire Ripcord cables. They are cheaper and I find that they shift smoother and last just as long. As a bonus they come in colors if that matters.