Use SmartActions or Juice Defender. Both go a LONG way in terms of battery for me. I get at least 14 hours out of my battery using JD. Also, don't be afraid to use wi-fi at work. It uses much less juice than 3G. It only becomes counter-productive when you aren't in a wi-fi area and it's constantly looking for the signal.
If I helped you in any way, don't be afraid to hit "Thanks"