Properly adding recognizable dates to RSS

[ev5unleash]

I have recently added RSS to my website, Over time i've added news and I've seen that the date of all articles stay at the same date on RSS Readers like Internet Explorer and Safari. I would like it so it will recognize the old and new articles by date.

<?xml version="1.0"?>
<rss version="2.0">
<channel>
  <title>ev5unleash News RSS Feed</title>
  <link>http://www.ev5unleash.com</link>
  <description>This RSS Feed is created to help you stay up-to-date with the news from ev5unleash.</description>
  <language>en-us</language>
  <copyright>2008 ev5unleash All Rights Reserved.</copyright>
  <lastBuildDate>Sat, 08 June 2008 1:00:00 -0400</lastBuildDate>
  <image>
   <url>http://www1.ev5unleash.com:1212/images/sitelogosmall.jpg</url>
   <title>ev5unleash</title>
   <link>http://www.ev5unleash.com</link>
   <width>144</width>
   <height>50</height>
  </image>
  <item>
   <title>(06/08/08) -  Twisted Steel software</title>
   <link>http://www1.ev5unleash.com:1212/homepage/news/060808.php</link>
   <description>ev5unleash has partnered with Twisted Steel Software, Check it out!</description>
  </item>
  <item>
   <title>(06/06/08) -  Php Problems fixed</title>
   <link>http://www1.ev5unleash.com:1212/homepage/news/060608.php</link>
   <description>With the help of Php Freaks from Phpfreaks.com ev5unleash has managed to fix php problems you might of occured.</description>
  </item>
  <item>
   <title>(05/28/08) -  Server Switch</title>
   <link>http://www1.ev5unleash.com:1212/homepage/news/052808.php</link>
   <description>We have received reports that some users could not reach our site at different locations and times...</description>
  </item>	
  <item>
   <title>(05/24/08) -  Server Switch</title>
   <link>http://www1.ev5unleash.com:1212/homepage/news/0524081.php</link>
   <description>As of 6:00 PM EST. We have switched our website to another server.</description>
  </item>	
  <item>
   <title>(05/24/08) - We will switch our site to a different server.</title>
   <link>http://www1.ev5unleash.com:1212/homepage/news/052408.php</link>
   <description>We will switch our site to a different server sometime today...</description>
  </item>	
  <item>
   <title>(05/16/08) - ev5unleash releases it's new theme of it's website.</title>
   <link>http://www1.ev5unleash.com:1212/homepage/news/051608.php</link>
   <description>ev5unleash released it's new version of the website...</description>
  </item>	
</channel>
</rss>