Exhibit 12.1

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES

(in thousands)

	For the Year Ended December 31,
	2001			2002			2003			2004			2005
Earnings (loss)—
Loss before income taxes	$	(10,090	)	$	(34,017	)	$	(29,789	)	$	(93,271	)	$	(88,593	)
Add fixed charges:
Interest expense on indebtedness		692			1,936			990			4,480			6,557
Estimated interest on rental expense		341			329			300			1,611			3,900
Amortization of deferred closing costs related to convertible notes		—			294			156			521			816
Amortization of discount on convertible notes		—			511			271			—			—
Total adjusted loss	$	(9,057	)	$	(30,947	)	$	(28,072	)	$	(86,659	)	$	(77,320	)
Fixed charges—
Interest expense on indebtedness	$	692		$	1,936		$	990		$	4,480		$	6,557
Estimated interest on rental expense		341			329			300			1,611			3,900
Amortization of deferred closing costs related to convertible notes		—			294			156			521			816
Amortization of discount on convertible notes		—			511			271			—			—
Total fixed charges	$	1,033		$	3,070		$	1,717		$	6,612		$	11,273
Coverage deficiency	$	(10,090	)	$	(34,017	)	$	(29,789	)	$	(93,271	)	$	(88,593	)