Tony,
I have a Dell Pentium 4 computer and an old Compaq Laptop and both work without problems without a powered hub for the USB. In fact, I have used as much as nine feet of USB cable without problems.
I did have problems at first because of other software stealing processor time away from the USB transfer between the PC and KN7000. Windows XP is particularly bad for this as it is constantly checking for "this and that" on the system. The result is that it causes stuttering of the WAV or MP3 file that you are trying to generate. There has been quite a bit of discussion about this in the past on the forums. If you can't find the past information, contact me by EMail and I'll research it for you.
Regards,
Walt