Aphex, I have been experimenting with software digital parametric equalization through foobar2k VST and have gotten quite excellent results from IIEQ. What is it you are actually wanting to do? In my case, I wanted to eliminate a peak in the upper frequencies and it worked out quite well. Are you planning on using the EQ for corrective measures or for subjectively different sound quality?
For corrective measures, the PEQ is better because you can accurately (reasonably for free software) the bandwidth, center frequency, and gain of the bandpass filter(s).
For subjective different sound quality, a hardware analog graphical equalizer may be preferable since you would be able to change the bands at your will with your fingers. The problem with this route is that many affordable graphical equilizers are 1/3 octave bands, and this may not be fine enough for you.
The software PEQ that I use has 10 bands that you can fine-tune each one of them.
Remember that you cannot really boost any frequencies as this will quickly increase the demands on the headphone driver and amplifier. With software PEQ, the situation with boosting is even worse as the signal clips/distorts within the music player (since most modern music is already at 0dB or worse). For some classical music that is recorded at -10dB, you can get away with boosting in the software.