SharePoint 2010 Branding: Change site actions and welcome menu arrows

Here's how you can do it. Hide the image and give our custom image element a background image. Look Like:

.ms-viewselector-arrow {
    background: transparent url('/PublishingImages/images/Arrow.png') no-repeat scroll 0 0;
    height: 4px; /* height of the image */
    width: 5px; /* width of the image */
}

.ms-viewselector-arrow img {
    display: none;
}