Resolved Can't reply from within Craigslist postings using Windows Mail under Vista

I can send and receive emails just fine from within the Microsoft Windows Mail program using Vista Home Premium. However, if I click on the link from within a posting on craigslist, I get a popup titled Windows Internet Explorer.
In the box it states:" Could not perform this operation because the default mail client is not properly installed "
I've always used Outlook Express but recently migrated to Vista and Windows 7 on several computers with no problems. This is the first time that I have been unable to use the reply to feature in Craigslist.
I haven't tried it elsewhere so I can't say for sure how pervasive this problem is.
Can anyone help me to install the mail client properly?
Thanks.

 

Thanks Pete. You're the greatest.
I went to IE> Tools> Internet Options> Programs. Under Internet programs I clicked on Set Programs, and then set your default programs.
Windows Mail was one of the ones listed.
I set it as default. It had only one of three defaults active, and prompted me to set all three. I did. I tried a random reply from within a Craigslist posting, and it works!
Thanks again.
I'll be marking this thread as resolved.