write.table with proper column number in the header

Did you notice that the file generated from write.table() in R has missed a tab (\t) in the top-left corner, when row.names=T (by default)?

I found the solution here:
http://stackoverflow.com/questions/2478352/write-table-in-r-screws-up-header-when-has-rownames

write.table("filename.xls", sep="\t", col.names = NA, row.names = TRUE)

Actually, the R document has stated it clearly:

By default there is no column name for a column of row names. If col.names = NA and row.names = TRUE a blank column name is added, which is the convention used for CSV files to be read by spreadsheets.