A common misunderstanding is that the write to spreadsheet.vi can be used to write to a spreadheet.xls file! The file generated should be called .asc for it is an ascii coded textfile with a format that can be read (imported) by most spreadsheet programs.
So formating is not an issue.
You can use the NI examples for writing to excel or from the developer exchange download our free library to communicate with excel. Our free library is donated to the developer zone.
It is called "Excel Toolkit (GOOP)" and I always find it searching on philips
greetings from the Netherlands