Winclip in Yahoo mail?

I just sent an e-mail with an attached file in the new Yahoo mail, and a message about buying Winclip popped up, and said Yahoo used that. I did just re-download Winzip and have some time on the free trial left, but is this some kind of way to force me to buy that software? Isn't there a free attachment option built in? I did some research, but came up with nothing. If anyone knows, let me know, please.

Edit - you know what? I just figured out how to go back to the classic yahoo by turning off javascript. Shouldn't have a problem anymore.

Really? Cripes, I should get that. I don't really download/send files that often, so Zip sufficed. But if it's free, I'm there.