Here's an easy way to convert that file of yours. I was having the same problem with my PDA. Here are the steps:
All you do is go into iTunes;
Go to Edit, Preferences
Click on the Importing tab
Under "Import Using," select MP3 Encoder
Next, right click on whatever song you want to convert (I usually create a playlist of the songs that I want to import onto my PDA, then just go into the playlist and select them all)
Then Left click on Convert Selected to MP3
Taa-Daa, that's all there is to it. Now you just through that playlist into your PDA, and your ready to jam out! And just a personal opinion, the iTunes software is very versitile...if you know how to use it!