What length IDE cables for mid-tower case?

I am going to purchase some round IDE cables for my Athlon 64 system that I'll be putting together. I don't think I've ever actually purchased IDE cables, and definitely not the round ones, so I was wondering if someone could tell me what would be a safe length for a mid-tower case (3-head cable)? I'm thinking 18", but maybe 24" to be safe. I think 36" is probably too long. I will probably use the 2 top-most drive-bays and the top slot in the HD rack.

Also, does the manufacturer of these round cables make a difference, or is a cable a cable? Thanks for any help you can provide.

36" is overkill and way too long. Depending upon how your MB setup and your mid tower case. An 18" should work for the lower 2 bays or get a 24" one for the upper two bays. I recommend you use rounded cables for neatness and airflow.