I just upgraded from A6 Commercial to A7. All the modules run except WED. I tried installing on two separate systems (one XP Home, the other Vista Ultimate)and got same result.

This could be a bug of the 30 days trial mechanism. Can you start the engine (acknex.exe) and look which startup message you got? Is your name indicated or do you get a "Trial version - xx days left" message?

Yes, installing the key file took care of the problem.

Is the version I've just downloaded the same as the public beta (7.03?) WED reads 7.01, SED 7.02.1 and MED 6.86.

The version distributed by ShareIt is 7.01, so you need to apply the public beta update to convert it to 7.03. The public beta seems to be stable, so I'd recommend to update it.

Can you post a link to the page on which I can find this update?

Public beta updates can be found on the update forum. - There is one recently known bug with the public beta: you can't publish .WDL scripts, only .C scripts, so use Version 6.60 for publishing WDL.