I'm assuming that you didn't fool around with any of the client settings and that it successfully updates when you launch it. If so, then it really sounds like you have a graphics card problem.
You can see the system requirements for the game here:
If you feel like your computer should be able to handle that, then when you launch the client, click on Options > Video > Graphics set them to Low, reduce Effects and Shadow a bit, set Terrain to Low, uncheck Water, set UI Cache to Off, click Confirm.
Try launching the game and see what happens. If it's all white, and you still feel like it's not your computer, then uninstall the Akamai installer and the game through Control Panel.
Download using one of the approved mirrors, such as the one here, and try again: