For anyone interested, I have writen a program to help you select current limiting resistors for your unipolar steppermotors.
I know it can be calculated easily with ohm's law but this is easier and great for newbies.
It also calculates powersupply minimum current rating based on the motor current and the number of motors used.
The best way to use it is to enter your motor and powersupply data, then hit calculate. Since resistors don't come in values to 2 decimal places, you can then select "I want to calculate motor current" and enter the closest available resistor size to calculate actual motor current based on the resistor you choose.
You can select transistor or FET outputs on your controller, and whether you want 2 resistors per motor or one with the center taps tied together.
Download it here:
www.e-zflight.com/files/stepcalc102.zip
Let me know if you download it, and how you like it.
Here is the screen shot.
Eric