i don't have n900, but the bar should be looking very good!.
i suggest to try it.
New loading indicator bar for the Nokia N900
Extract all 16 images and put them in usr/share/icons/hicolor/scalable/hildon and overwrite.
Reboot to see new loading bar.
Download:
http://adf.ly/3Xzo
http://www.deviantart.com/download/167776286/New_loading_indicator_bar_N900_by_biggzyn80.zip
