I've never had a problem with stuff that Amazon sells and ships. The third party sellers are a different story.
Before you buy the Xsi, do you want to read this link?
http://www.1001noisycameras.com/2009/03/new-canon-500d-digital-rebel-coming-on-march-25.html That could explain a price drop. It also looks like it may have an articulating hi res LCD.
But, its just a rumor.