Yes - definitely After Effects. This tutorial:
will show you how to do it. You start by creating the vectors in Illustrator, then import them and animate them using the Stroke effect in After Effects.
I would warn you, however, that from a useability standpoint animated backgrounds for PowerPoint slides are usually a really, really bad idea - folks will be too busy watching your animation to pay attention to what you're presenting, so unless it's for a kiosk-style presentation you should really think hard before you use an animated background. Remember - the human eye evolved to track motion, so that's where it's going to go. You can use this to your advantage (animated reveals will draw the viewer's eye to the current bullet point) but it's easy for animations to become distracting.