You get slightly different sizing from different browsers for non-specified units of measure (such as input type=text size=). Just start taking a couple of pixels off the floating box widths until it fits.

Actually, the problem is that the height and width of text input areas is that they are dependent on font-size, and different browsers so often give you different font sizes. One thing that might help is to specify a class like input.text {font-size: whatever; line-height: whatever;} and do it in "pt", then put the class inside the input (ie 'class="text"').

Of course, if consistant with your design, you can also give one column a flexible width and/or use percentages for column widths. IE7 (unlike ie6) recognizes minimum width, in my limited experience.