Monitor Connection Problem

I have a new Inspiron 530 and a new Viewsonic 2255wm.  When I use VGA cable, everything works fine.  However, when I use DVI cable, I have the following two problems:

 

1.  The monitor does not turn on during the Windows Vista boot-up until Windows is fully loaded.  The first thing I see is Windows Log-In screen - I don't get to see Dell's Logo and Windows loading.

 

2. The monitor does not wake up from power saving mode after computer wakes up from the Sleep Mode.

 

Please note that I don't have above issues when VGA cable is used.  However, the image quality is much superior when DVI cable is used. 

 

Please help.  Thank you.