Is there a way to make it so that your blog only displays posts from one category as the front page? I'm using Wordpress 2.5
Nopes,its not possible. But you can make a static post to always appear in your frontpage. Also you can use WP-STICKY for making few posts sticky aor announcements. So you can select all the posts of that single category and then make all of them sticky,so that all of them appear in your frontpage. Ok dude.
Actually it is and it's fairly easy If you want to use a plugin then you can try Advanced Category Excluder. Just exclude all catogories except the one you want on the home page. You can also just place an if statement inside the wordpress loop. So it would look something like if have posts{ if category=x { display posts} end if end if the wordpress codex explains how to do it here