CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) (USD $) In Thousands, except Share data	3 Months Ended		6 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Condensed Consolidated Statements of Income (Unaudited) [Abstract]
Revenues	$ 40,025	$ 35,277	$ 76,028	$ 70,230
Cost of revenues	18,004	15,527	34,784	30,696
Gross profit	22,021	19,750	41,244	39,534
Operating expenses:
Research and development	3,008	3,296	6,462	6,374
Sales and marketing	9,335	8,408	18,487	17,041
General and administrative	4,495	2,652	7,914	4,776
Total operating expenses	16,838	14,356	32,863	28,191
Income from operations	5,183	5,394	8,381	11,343
Interest and other income (expense), net	56	757	350	652
Income before income tax provision	5,239	6,151	8,731	11,995
Income tax provision	1,918	2,402	3,196	4,666
Net income	$ 3,321	$ 3,749	$ 5,535	$ 7,329
Net income per share:
Basic net income per share (in dollars per share)	$ 0.15	$ 0.17	$ 0.25	$ 0.33
Diluted net income per share (in dollars per share)	$ 0.15	$ 0.17	$ 0.24	$ 0.32
Shares used in the calculation of net income per share:
Weighted average common shares outstanding - basic (in shares)	22,290,000	22,317,000	22,484,000	22,264,000
Weighted average common shares outstanding - diluted (in shares)	22,564,000	22,691,000	22,850,000	22,736,000