The simplest way to sync iTunes with your HTC Aria, (on Windows), is to:
1. Mount the phone as a drive
2. Create a Music folder on the phone, (which showed up as E: for me).
3. Create a desktop shortcut to c:\Documents and Settings\myuser\My Music\iTunes\iTunes Music
2. Double-click the shortcut, and line up the two windows so that you can see the iTunes directory, and the phone.
3. Copy-and-paste folders and files over to the Music folder on the phone
I'm guessing that DRM'd music files will not play on the Aria, but haven't tried it myself.
With a little side of applesauce...
©2006 Shannon Eric Peevey