Excel sheet can write only up to 256 columns - C# (Office Interop)

Question

Hi,

I am creating an excel spreadsheet using C# (Office Interop). In the Excel sheet I need 600 columns.

The program can write up to 256 columns. After that it gives me a memory error. 

How can I write all 600 columns in the spread sheet using my program?

I am happy to use Office Open XML if anybody can provide me an example to convert XML to Excel using Office Open XML (I heard that Office Open XML is better than Office Interop)?

Thanks