Excel has row limit 65536/1,048,576. If you have installed the excel 2003 then it limit is 65536. So you need to upgrade the excel later that 2003 version for getting the more row limit. 2007/2010 row limit is 1,048,576.
If in case your data is bigger than this count then easiest way is then you can split the file in 2 parts.
For splitting you can open the file in notepad and divide the data in 2 different notepad file and then save in .csv format. Try it.
http://forums.asp.net/t/1189246.aspx
Worksheet and workbook specifications and limits
http://office.microsoft.com/en-in/excel-help/excel-specifications-and-limits-HP010342495.aspx