rss收录聚合器做法？

Question

下面是一个RSS的xml文件，我想用.net读取并存储<item>这个结点下的每个子节点。在存储这组结点之前，我还行比较一下<pubDate>结点（只存储一定时间之后的内容）。<?xml version="1.0" encoding="utf-8" ?>
<!-- generator="FEEDCREATOR_VERSION" -->
<rss version="2.0" xmlns:sns="http://blog.sina.com.cn/sns">
    <channel>
        <title>Blog</title>
        <description></description>
        <link>http://blog.sina.com.cn</link>
        <lastBuildDate>Mon, 27 Apr 2009 15:00:03 GMT+8</lastBuildDate>
        <generator>FEEDCREATOR_VERSION</generator>
        <language>zh-cn</language>
        <copyright>Copyright 1996 - 2009 SINA Inc. All Rights Reserved.</copyright>
        <pubDate>Mon, 27 Apr 2009 07:00:03 GMT+8</pubDate>
        <item>
            <title>标题</title>
            <link>原链接</link>
            <description>内容</description>
            <author>作者</author>
            <pubDate>Sun, 26 Apr 2009 16:03:06 GMT+8</pubDate>
        </item>
        <item>
            <title>标题</title>
            <link>原链接</link>
            <description>内容</description>
            <author>作者</author>
            <pubDate>Sun, 26 Apr 2009 16:03:06 GMT+8</pubDate>
        </item>
        <item>
            <title>标题</title>
            <link>原链接</link>
            <description>内容</description>
            <author>作者</author>
            <pubDate>Sun, 26 Apr 2009 16:03:06 GMT+8</pubDate>
        </item>
        <item>
            <title>标题</title>
            <link>原链接</link>
            <description>内容</description>
            <author>作者</author>
            <pubDate>Sun, 26 Apr 2009 16:03:06 GMT+8</pubDate>
        </item>
 </channel>
</rss>