In an effort to compete with Sun Microsystems and Hewlett-Packard, IBM is expected to announce Tuesday it will <A HREF="http://www.cio.com/blog_view.html?CID=23453">expand its line of servers powered by chips from AMD.</A> IBM already sells low-end servers with AMD's Opteron chips, so the move will allow the company to offer more choice in its high-end, commercial line. IBM would not confirm the details, but said its systems division, responsible for designing servers and chips, would announce new products and partnerships in "our biggest announcement of the year," according to IBM spokeswoman Joanna Brewer.