I don't recall the last time mine ever said "DROID!" on startup; instead it plays the notification called "On The Hunt."
I assume if you're talking about the sound that plays when the lock screen first appears, all that uses is your default notification ringtone in Settings, assuming it's one of the default tones as your phone will not play custom tones until the SD card has been found (which would be after initial startup). So you can make it whatever you want. From there you go into any applications that use notifications and set a custom notification for them. My default notification tone is On The Hunt but for text messages I use the Transformer sound and email tones are silenced. Probably just restated what's on the thread that link pointed to but oh well, didn't feel like reading it.
I'd like to be able to copy personalized tones to the phones folders but I guess that's what rooting is for. I found a bunch of sound clips from the HAL9000 and I was interested in integrating them with the Droid for a theme.