Disable low-battery warning, specifically on XOOM I would like to disable the low-battery warning on my XOOM without rooting. It's a pretty obnoxious sound compared to other phones I have used.  By rooting, I can replace /system/media/audio/ui/lowbattery.ogg with an empty sound file, but I'd rather not take that route just yet.

Is there an Android app for replacing sounds or just forcing it to not play the existing sound?
No, there will not be an app that changes it since it is in the system. You have to have root to change system settings.  Once you root, there may be a developer who has a file you can flash that will do it for you. I am sure that if you thought it was annoying, so has a developer. It's only slightly easier than changing it yourself.