CS4 vs CS5 compatability

[Barmyfluid]

Hi - I'm authoring an educational resource which will be offline HTML with Flash for video and activities (based on the Open University DVD resources).

I'd rather that starting it wouldn't force too many users to upgrade their local Flash player, and my question is, does authoring with CS5 automatically result in an animation that requires the most up to date player, or is it only when you use new CS5 features?

I only have an old CS3 at the moment and need to upgrade, but its about the same to buy CS4 as CS5 on an educational license (unless anyone has a good supplier for CS4) - I'd buy CS5 but don't want it to be on the cutting edge if it causes more grief in the classroom from having to upgrade players.

BTW, anyone know where you can still bu legit copies of CS3 other than ebay?

Thanks in advance
Andy

[dagger_69]

I create flash banners with lots of effects and actionscripts for years and i moved trough CS3, CS4, CS5 to CS5.5. There was small actionsciprt problems, but nothing big. Because of different ad campaigns specifications, i export the .swf with Flash Player 9 or even Flash Player 8 and there are no problems. So when using Flash CS5, just export the .swf in lower Flash Player than the newest one. Also ActionScript 3 starts with Flash Player 9. And in CS5 there are cool 3D tweens, that are in the built in tools. They require AS3