HELP! Product Photography--What am I doing wrong?

Hi, I am new to this forum and am sooo glad to have discovered this site!
I am a beginner to studio & lighting so I was practicing / taking test shots of clothing (pants & tops), to prepare myself for my first catalog shoot.

Here's my setup: I have 02 lights--Bowens 500watts (one softbox, one umbrella), Camera: Canon EOS 10D set to take images on RAW, White Balance set on Flash, Color Parameter set on RGB.
The products: pants & tops were setup lying flat directly onto the MDF board which I painted matte white. The white MDF board serves as my background.

To view the results faster, I connected my camera to my Mac and directly download/save the images (using Canon's image capture software).

My question is, how come the background comes out as a light greyish hue--not white. I tried increasing my main light's power but the image that comes back is washed especially on the side close to the main light.

Also, when I convert the RAW files to 'eps' and then open it on Adobe Photoshop 7, the light greyish hue becomes pinkish. Where did I go wrong?

Appreciate your advises , mates! :-)