It is up to you. Old serial cable works with win7 32 and 64bit windows if you have real serial port on computer. Both cables supports same plcs.
Anyway, old twidosoft version needed com port to be below 8, if you use usb cable, you only need to configure usb to use some com port from 2-8 at device manager. (If you have lot of bluethoot drivers installed at computer, it can be little bit tricky).
With newer twidosuite there is not maybe this issue?