Photoshop version compatibility

Hi,
I have made a web graphic in photoshop CS4.

when the psd. is tried to be opened in photoshop 6, it shows an error message “could not open. not enough memory(RAM)”.

How do i save a psd with backward compatibility?

Why not ask the client to upgrade? PS6 is ancient . . . September 2000…!

Is there any free software that can open photoshop psd files?

Thanx for your help. You are right about the huge difference.
I had no idea my client had phtoshop 6!

It would appear that GIMP can open PSD files with a bit limited functionality, based on [URL=“http://ubuntuforums.org/showthread.php?t=825934”]what I’m reading.

I’ve never tried to take a PSD so far back before, but some Googling turned this up: How do I Save a Photoshop File for an Older Version?

In addition, I found a discussion about PSD backwards compatibility which may shed some light on the subject for you.

If those don’t help I’d probably say that such a large variation between versions will make it impossible to maintain compatibility. I can understand sitting on a version of PS for a few years to save money - but who in the world still uses PS6 anyway? It might be time to consider upgrading.