IBM Product to Challenge Data Storage Leader EMC  SAN FRANCISCO (Reuters) - IBM &lt;A HREF="http://www.reuters.co.uk/financeQuoteLookup.jhtml?ticker=IBM.N qtype=sym infotype=info qcat=news"&gt;IBM.N&lt;/A&gt; on Friday will take  aim at the heart of data storage equipment leader EMC Corp.'s  &lt;A HREF="http://www.reuters.co.uk/financeQuoteLookup.jhtml?ticker=EMC.N qtype=sym infotype=info qcat=news"&gt;EMC.N&lt;/A&gt; market with a product that will allow EMC buyers to  switch to IBM.