You can get just the Baseband update, look in the Hack section....or just use this link to go to the thread..I don't have the official 2.1, but have any of you noticed improved call quality? That's the only reason I've considered unrooting to take the official update.
http://www.droidforums.net/forum/droid-hacks/33703-major-baseband-news-alldroid.html
It's an update.zip file to use with sprecovery so you would have to be rooted and have sprecovery installed. Updates the Baseband, you'll need to re-activate your phone which takes less than 1 minute. Will not affect your Rom image, data, applications, settings, etc....it just updates the Baseband.