For sure. Just use the audio editor of your choice (Audacity is free) and lower the gain...
If your audio player supports a replay gain feature you could also use that.
I personally don't mind if some songs are louder because I only listen to entire albums, never to single tracks and I'll be sure the ME adjusted all levels appropriately.
I have Windows XP Pro, sp3 and use Winamp 5.572 to play my music.
I have all my songs on my hard drive, in "My Music". I haven't noticed a difference in any of the other hundreds of songs I have but there is one that is much louder than the rest. So loud that I have to rush to turn it down. If I can't fix it I'll have to remove it. I have a tag editor but for this I would think you'd need to mess with the music file itself.. Is there anything I can do with it?