Do Not Rule Out Lower-Priced Apple iMac--Analyst  SAN FRANCISCO (Reuters) - Apple Computer Inc. &lt;A HREF="http://www.reuters.co.uk/financeQuoteLookup.jhtml?ticker=AAPL.O qtype=sym infotype=info qcat=news"&gt;AAPL.O&lt;/A&gt;  could decide to sell a lower-priced of its Macintosh computer  to attract consumers already enamored of its iPod music player  and annoyed by security problems with Windows PCs, Piper  Jaffray analyst Gene Munster said on Thursday.