UPDATE: I now use RSS Import on my sites.

FeedList is my fav RSS feed plugin for WordPress. The plugin developer is very friendly and constantly updates this plugin with new features. Here are the settings I usually use for implementing it:

	< ?php
		feedList(array("rss_feed_url"=>"INSERT RSS FEED URL HERE",
						"num_items"=>4,
						"show_description"=>true,
						"random"=>false,
						"description_separator"=>"",
						"sort"=>"none",
						"new_window"=>true,
						"show_date"=>true,
						"max_characters"=>140,
						"max_char_wordbreak"=>true
				)
		);
	?>

Another RSS WordPress plugin that looks good is FeedWordPress. Also check out RSSImport.

This post shows you how to do the RSS import manually:

http://bavotasan.com/tutorials/display-rss-feed-with-php/