Yes I see this 'behaviour' often. In designer it can look all pretty, yet in IE it looks 'terrible'.
IE renders your form more true, whereas designer, alllows you to fudge things a little.
The one that oftens gets me is borders. I will often have to check my field/row heights. Normally one field in a row can be a different height i.e. not auto when all the others are set to auto height. I can only see this when viewing in IE. In designer all looks perfect.