Writing .xlsx files

Dear all,

I have been looking for possibilities to read and write Excel 2007-files 
in and from R.
The 'reading' part is ok through odbcConnectExcel2007 and sqlFetch(RODBC).

For 'writing' I thought of using sqlSave in the same package, but it 
does not work (I think because this function starts from an existing 
file). Is there a workaround for this, or are there other plausible 
options for writing .xlsx files?

With kind regards,

Katrien

PS: I found some information about RExcelInstaller, if this is something 
that would solve my problems could someone describe how it works (the 
user manual did not help me very much).