I couldn't find the answer to this in the archives.
I was having problems getting my site in an RSS reader, so I went to this vaidator site: http://www.feedvalidator.org/check.cgi?url=
They said I had three problems:
1. I didn't have a title (I'm using a logo gif) --> I put in a dot
2. line 87 of wp-blog-header.php din't have a hyphen between "Last Modified" --> I put one in
3. my content typs was "text/html" and it probably should be something like "application/rss+xml" --> I changed it.
It says it validates now, and I was able to get the feed in the RSS reader I was working with, but now when I click on the RSS link on my site it tries to download the file instead of rendering it in the browser. The RSS comment seems to work fine, though.