If you have indeed formatted both your system and sdcard you are going to have to do a few things to get back up to speed. I will not go into too much detail here, but doing some searches on this site (or on Google) for each step, you will get the details you need.
1) Flash the Moto Droid 2.01 SBF to your device to get your /system repopulated.
2) Go to your settings and find the Memory section. Unmount then format your SDCard.
3) Flash the Moto Droid 2.1 update.zip to get up to date OS
You now have a working stock Droid with the latest official 2.1 OS.