Exhibit 12.1

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES

(in thousands)

	For the Year Ended December 31,
	2006			2005			2004			2003			2002
Earnings (loss)—
Loss before income taxes	$	(78,298	)	$	(88,593	)	$	(93,271	)	$	(29,789	)	$	(34,017	)
Add fixed charges:
Interest expense on indebtedness		9,574			6,557			4,480			990			1,936
Estimated interest on rental expense		3,979			3,900			1,611			300			329
Amortization of deferred closing costs related to convertible notes		827			816			521			156			294
Amortization of discount on convertible notes		—			—			—			271			511
Total adjusted loss	$	(63,918	)	$	(77,320	)	$	(86,659	)	$	(28,072	)	$	(30,947	)
Fixed charges—
Interest expense on indebtedness	$	9,574		$	6,557		$	4,480		$	990		$	1,936
Estimated interest on rental expense		3,979			3,900			1,611			300			329
Amortization of deferred closing costs related to convertible notes		827			816			521			156			294
Amortization of discount on convertible notes		—			—			—			271			511
Total fixed charges	$	14,380		$	11,273		$	6,612		$	1,717		$	3,070
Coverage deficiency	$	(78,298	)	$	(88,593	)	$	(93,271	)	$	(29,789	)	$	(34,017	)