Here is where I got my PDF viewer. Scroll down, and look for:
"adobe acrobat reader 2.0 for HPC2000" or
"adobe acrobat reader 2.0 for ce.net 4.1 devices"
You should try both, but the second one is supposed to work for you.
I use TCPMP for a media player. You can find it
here. You'll need to change the video setting on the Airpanel becuase the default setting won't work with TCPMP. Don't worry, one of the other two will.
One nice thing about the 4.1 firmware is that it has the drivers for the graphics chip. The 3.0 doesn't have them.