Upgrading video card

Bear with me as I'm a technology novice...

I have a Dell Inspiron 6400 which I use for college, work and leisure.

I recently tried to install a game but was told that the video card wouldn't support it. It recommended upgrading from a 32mb video card to a 64mb video card.

Can anyone tell me how to go about upgrading the video card?

Here is a guide of what to consider when upgrading.

I'd hang onto the receipt just in case. Sometimes the new card just doesn't work out.