http://forums.macosxhints.com/archive/index.php/t-63641.html May be of some help.
Unfortunately I will no longer be of any help tonight.
My zipping is working fine on Leopard.
Try this generic zip file created with ALZip in Winblows; here.
Right click and hold down option when the contextual menu appears.
Then just choose "Always open with", and BOOM! job done.
Do you have it installed?
And yea, stuffit.
thx, that works http://www.putfile.com/pic.php?img=7048217
but my orginial file is a winzip attachment, should that make any difference ?