Hi renny krupinski, i have a HTC Magic and the first 2 days i have the same problems with batery, but i change the situation, the only thing you can try is:
1- put the display brightness at 50%
2- no use the tacticle feedback
3- use sometimes 2G networks
4- Always bluetooth of
5- Use the Wirless only when you need
6- No charge the phone power off
This is many things you can do, but donīt forget... HTC MAGIC is a big machine and very powerfull. (sometimes the batery canīt resist)