I had my custom EQ set to 4-3-2-4-7. That is until I got my Sennheiser PX100 headphones this past friday
Now, I have the EQ off. Bass boost: off. Smart volume: off.
If you want good sound, do your zen (and your ears) some justice and invest a little more money into good headphones.
As far as normalizing your mp3s... I think that's a BAD idea. Professionals with lots of expensive gear optimize the music you're paying for. The last thing you should do is mess with the levels of your mp3. For example. My g/f copied two Linkin Park CDs she had. She used the normalizing setting of her ripping software on one album. The other album, she didn't normalize. You listen to the two albums back to back, and you can hear a definite difference. The uneffected mp3s are loud and dynamic. The normalized mp3s are low and flat.