Disclosure, an Amendment of FASB Statement No. 123 in the second quarter of 2003, and restated prior periods at that time. Because the fair value recognition provisions of SFAS No. 123 and SFAS No. 123(R) were materially consistent under our equity plans, the adoption of SFAS No. 123(R) did not have a significant impact on our financial position or results of operations.

We changed our method of calculating the fair value of new stock-based compensation awards under our stock plans from a Black-Scholes model to a lattice-binomial model on January 1, 2007. We continue to use a Black-Scholes option model to determine the fair value of employee stock purchase plan shares. The lattice-binomial model has been applied prospectively to options granted subsequent to January 1, 2007. The lattice-binomial model requires the input of highly subjective assumptions, including the option’s price volatility of the underlying stock. Changes in the subjective input assumptions can materially affect the estimate of fair value of options granted and our results of operations could be materially impacted.

 

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Expected Volatility:    Our computation of expected volatility is based on a blend of historical volatility of our common stock and implied volatility of tradable forward call options to purchase shares of our common stock. Our decision to incorporate implied volatility was based on our assessment that implied volatility of publicly traded options in our common stock is more reflective of market conditions and, therefore, can reasonably be expected to be a better indicator of expected volatility than historical volatility of our common stock.



 

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Suboptimal Exercise Factor:    Our computation of the suboptimal exercise factor is based on historical option exercise behavior and the terms and vesting periods of the options granted, and is determined for both executives and non-executives.



We grant stock options to our employees on a monthly basis. We have elected to grant all options as non-qualified stock options which vest immediately. As a result of immediate vesting, stock-based compensation expense determined under SFAS No. 123(R) is fully recognized on the grant date and no estimate is required for post-vesting option forfeitures. See Note 7 to the consolidated financial statements for further information regarding the SFAS No. 123(R) disclosures.

Income Taxes

We record a tax provision for the anticipated tax consequences of our reported results of operations. In accordance with SFAS No. 109, Accounting for Income Taxes, the provision for income taxes is computed using the asset and liability method, under which deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the financial reporting and tax bases of assets and liabilities, and for operating loss carryforwards. Deferred tax assets and liabilities are measured using the currently enacted tax rates that apply to taxable income in effect for the years in which those tax assets are expected to be realized or settled. We record a valuation allowance to reduce deferred tax assets to the amount that is believed