My question is really quite simple: how legal is to download beta software? Working key is another subject but I mean the sofware itself? Even if I dont own a legal key.
Specially I mean office 12 beta because in another forum where I actively participate (warez is a big no-no there) I posted some screenshots and a link where I had gotten them and I was blamed for handing out pirated stuff. I kind of remember a little bit that betas are for public use if they aren't covered with NDA.

I tried to search about this subject but with no luck.
So a bit of advice is needed from you

Depending on the beta, it could be illegal. The Office 12 Beta EULA probably says something about not distrubuting it or discussing it with people outside the beta program.

Downloading Beta Software is the same as downloading any other software/warez.

Unless of course that it's an open beta which isn't invite only/etc.

Um, no. You can distribute any beta software, unless your contract states that you cant. Besides, companies gain more when more people are testing their software. BUT, there are cases where beta software is internal and should remain that way.

You can distribute anything unless the contract says otherwise

Erm, every beta "contract" (Usually in forms of an NDA/EULA) say that you can't.

And, if it isn't under NDA or EULA... Then it's usually already an open beta.

Unless if you can give me a closed/private beta without an EULA or with an EULA that allows the person to distribute it. (Example, Windows Vista specificially says "Do not distribute".)

Taking Vista as example, You're NOT allowed to share the software, however, making screenshots and talking about it, is allowed

I havent seen any beta (apart from Gmail ) that lets you share it unless its also available from the website of the owner also...

Some beta's say not to discuss, such as AOL's beta software.