I have been using OO for some times now, there are some things I like it, such as the ability to export to PDF, and a simple read and save will reduce PPT file size, but the bad is a small Excel file will become 4 times as big once edited. I have a simple worksheet with non English characters in a small table about 7x30, no formula and no longer than 20 characters average in each cell, a few do have about 50 characters, but I don't think this will make a big different.
For example :
Original Excel : 21K
Open and save in ODF becomes 17K
Save as Excel becomes 74K
This is not a big problem with small file, but bigger file will be trouble to me as I've a slow line.
Do you Yahoo ? No I hiccup only ;p