@davidlliu: Excel has a built in limitation of 65535 rows (unless you are using 2007+). This limit is per worksheet, not workbook. Technically you could create 65535 rows on work sheet #1, add a new worksheet and continue adding rows. Repeat action until done.
I had a situation where the customer dictated that the final data be contained within a excel formatted document. While I warned them trying to fit 11 GB of data into Excel was insane, it is technically possible. It is very impractical. I would recommend keeping the number of worksheets per workbook to a small number as things tend to get out of hand.
