tighter controls over discretionary spending and greater use of outsourcing solutions. However, education revenues and expenses have increased in recent periods in comparison to the corresponding periods of the prior year as a result of additional education offerings related to our acquired products.

 

Acquisitions

 

An active acquisition program is another important element of our corporate strategy. Over the last four fiscal years, we have invested billions of dollars, including $9.4 billion in fiscal 2008, to acquire a number of complementary companies, products, services and technologies such as BEA Systems, Inc. in fiscal 2008, Hyperion Solutions Corporation in fiscal 2007, Siebel Systems, Inc. in fiscal 2006 and PeopleSoft, Inc. in fiscal 2005. We believe our acquisition program supports our long-term strategic direction, strengthens our competitive position, expands our customer base, provides greater scale to accelerate innovation, grows our revenues and earnings, and increases stockholder value. We expect to continue to acquire companies, products, services and technologies. See Note 2 of Notes to Consolidated Financial Statements for additional information related to our recent acquisitions.

 

We believe we can fund additional acquisitions with our internally available cash, cash equivalents and marketable securities, cash generated from operations, amounts available under our existing debt capacity, additional borrowings or from the issuance of additional securities. We estimate the financial impact of any potential acquisition with regard to earnings, operating margin, cash flow and return on invested capital targets before deciding to move forward with an acquisition.

Critical Accounting Policies and Estimates

 

Our consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (GAAP). These accounting principles require us to make certain estimates, judgments and assumptions. We believe that the estimates, judgments and assumptions upon which we rely are reasonable based upon information available to us at the time that these estimates, judgments and assumptions are made. These estimates, judgments and assumptions can affect the reported amounts of assets and liabilities as of the date of the financial statements as well as the reported amounts of revenues and expenses during the periods presented. To the extent there are material differences between these estimates, judgments or assumptions and actual results, our financial statements will be affected. The accounting policies that reflect our more significant estimates, judgments and assumptions and which we believe are the most critical to aid in fully understanding and evaluating our reported financial results include the following:

	• 	Revenue Recognition

 	

 	• 	Business Combinations

 	

 	• 	Goodwill and Intangible Assets—Impairment Assessments

 	

 	• 	Accounting for Income Taxes

 	

 	• 	Legal and Other Contingencies

 	

 	• 	Stock-Based Compensation

 	

 	• 	Allowances for Doubtful Accounts

 

In many cases, the accounting treatment of a particular transaction is specifically dictated by GAAP and does