Should an animated header be in flash or javascript?

Question

I work at a small website building company and on one of our clients website we have a flash animation in the banner. The animation is rather chunky being 4 megabytes. The client has recently requested a rebuild of the site which would again include an animated header. We were thinking about this time not building the header in Flash (or actually having it build in flash, since none of us can actually do flash), but building it ourselves in Javascript (with jQuery().animate() and plugins).

Is this a bad idea? Is flash better for an animated header? I understand you have more options, but you also require users to download flash player while Javascript is widely available.
Also it is a quite simple animation, it mainly consists of text popping in and out and some images moving around/fading in and out.

This should be quite easy using jQuery right (I consider myself quite experienced with jQuery), why would we choose the flash approach over the javascript/jQuery aproach?

Also if we choose the Javascript approach, what is the best way to make sure the animation doesn't affect anything else in the page? Will doing the complete animation inside an absolutely position div do the trick?

Edit
When I said banner, I actually meant Header.

Answer 1

In this order:

1. Don't use anything animated on a web page. It looks like an ad and distracts from the content. It's just irritating.

2. Flash is build for animations. Use it if the knowledge is there.

3. Try JavaScript and watch the CPU. We made a simple slideshow with jQuery and the PC starts the fan after the first run through it. Think about limiting the animation, so that it doesn't roast a user's computer if he leaves the room for a bathroom break.

Answer 2

You might also try animated GIF. Some might consider it ancient, but it is very portable, small, and gets the job done.