Setting the width of a column in a View

Insert a min-width attribute into the header tag
<th style="width: 251px; white-space:normal; min-width:251px;">

Insert a min-width attribute into the cell tag
<td style="width: 251px; white-space:normal; min-width:251px;">

Use the same value for obvious reasons. You can use SP Designer to help you decide what the values should be. Just expand the column until it's the desired width a tai a note of the value.