None of the ways it was done in XP work. Nobody has been able to answer this, so far. I can't even open links to emails.
I already have Yahoo IM and I have the toolbar that is supposed to make yahoo available to choose as my default. Doesn't work. I actually HATE W7! Everything about it is so ... HARD!
Trevor
Favorite Answer
I have Vista, but I'd assume the process is extremely similar to Windows 7.
First, try right-clicking on the start button, then click properties.
In Vista, you'd go to the Start Menu tab and click customize. You may have to search for a similar option in W7.
Then there should be an option to show an e-mail link. Next to that you can choose which e-mail is your default.
If this doesn't work, then you can download Yahoo Messenger and it should automatically make Yahoo your default.