You certainly can reorder the rows in the BOM table, but I prefer to use the "Follow Assembly Order" option in the Property Editor for the BOM Table and rearrange the order of the components in the assembly file. BOM tables (like any other SW table) can behave quite unexpectedly at times. I find it best to leave them in their default state as much as possible. Remember that in the assembly you can reorder the list in the Feature Tree and use the Alt key while dragging to make sure components don't get added to a sub-assembly by mistake. Also, once you have selected "Follow Assembly Order" you can no longer rearrange their order on the BOM table.
You can drag & drop them in 2010 as well. Make sure that you toggle OFF the follow assembly order or it won't allow you to reorder them. Also for those that use follow assembly order, there is a bug in 2010 that doesn't keep items in order of the assembly. This was fixed in SP2.1.