You can go the easy way and look at the board layout, hit print and then just put the IC over the print out, see if it matches. If you want to be more accurate and absolutely sure it's correct, then open the library containing the 328 and look at it in there, you can measure the distances yourself.
In the Control Panel, open the Libraries section and find the library containing the 328, right click and select Open
The 5th icon reads 'Edit a package', click on it and find the 328 in the list and double click it.
This will open it in the editor where you can see exactly which pads are numbered what and what the spacing is. You can either measure it by drawing another line between the center of the pads, or simply by looking at two adjacent pads and pull up the properties for them. Look at their position and subtract the numbers, see if it matches what the datasheet says.