For the record. The 6-pin IDC connector for the ISP cable is Mouser 649-71600-006LF. The 10-pin IDC connector for the JTAG cable is Mouser 649-71600-010LF. The 10 conductor gray ribbon cable is Mouser 523-191-2801-110FT. I would use this for both the ISP and the JTAG cables. Strip the last four conductors off of the 10 conductor ribbon for the ISP cable. An inexpensive IDC crimping tool is Mouser 382-0214. It's not necessary to use this, but it's not a bad deal for $18.51 each.
I would keep the cable lengths to 6" or under for each cable.