iWorks 06 backward compatible with older version?

[Reader]

Apple says you have to have 32 meg of VRAM to use the new versions of Pages and Keynote.

This seems very odd. I can understand you would need that for some of the new visual effects in Keynote, but why require that for Pages?

It would be useful to know if you really need that much VRAM to run the programs at all, or if some of the Keynote effects just don't work well.

I also would like to know if files created with the new versions can be opened/used in the older versions.

[Reader]

I just found this useful report

<a href="http://www.keynotepro.com/support/iWork_Update-06.html">iWork upgrade report</a>

that answers part of my question. iWork 06 introduces new file formats that are not directly backward compatible with the older versions, but you can save them in iWork 05 format.