We had $454.7 million of cash and investments on December 31, 2007, consisting of $338.9 million of cash and cash equivalents and $115.8 million of available-for-sale securities. Although these investments are subject to the credit risk of the issuer, we manage our investment portfolio to limit our exposure to any one issuer or industry. Substantially all of the cash equivalents are money market securities from domestic issuers. All of our available-for-sale securities are high-quality bonds that are exempt from U.S. federal income taxes. Because of the credit risk criteria of our investment policies and practices, the primary market risks associated with these investments are interest rate and liquidity risks. We do not use derivative financial instruments to manage interest rate risk or to speculate on future changes in interest rates. A rise in interest rates could negatively affect the fair value of our investments. We believe a reasonable near-term change in interest rates would not have a material impact on our future investment earnings due to the short-term nature of our investments. As of December 31, 2007 we had approximately $50.5 million of auction rate securities classified as available-for-sale securities on our balance sheet. We made the decision during the fourth quarter of 2007 to sell or exit these at the next auction date. As of January 31, 2008, we had no investments in auction rate securities.
