Wow,
Great replies guys and quick, I love to see very thing- a new Z owner being helped into the ZUG community!
The only thing I can add to the above is that you may need to charge the battery for a full 24 hours before the icon properly reflects the exact charge. There have been several C860 owners who have had a similar experience to what you are describing. They overcame it by completely charging their battery and conditioning it before breaking into a normal charge/usage cycle.
In case you don't know, to condition your new Z 6000 battery completely charge it for 24 hours. Then unplug your Zaurus from the wall and use it until the battery is completely depleted. Then plug it back in and recharge it until it indicates it's completed the charging cycle, (you do NOT have to charge it for a full 24 hours this time.) Then repeat the process until you have done it 4 complete times.
At that point your battery applet should be accurate at all times. To keep your battery operating at peak efficiency and your applet accurate make sure you completely deplete and then completely recharge your battery, leaving it to charge overnight at least and 24 hours if possible, once a month.
Welcome to the 6000L forum btw!
Be Safe,
-NeuroShock