How to change the company logo on vtiger CRM header?

To change the Vtiger Logo in the Header replace the below images
themes\softed\images\vtiger-crm.gif (For theme Softed)
themes\bluelagoon\images\vtiger-crm.gif (For theme Bulelagoon)
themes\alphagrey\images\vtiger-crm.gif (For theme alphagrey)
themes\woodspice\images\vtiger-crm.gif (For Theme woodspice)

Fonte:
http://wiki.vtiger.com/index.php/Installation_How_To's