Excel 2010 has 1 million rows, this is pretty good for those of us who were frustrated with the mere 36,000 in earlier versions.
1 million rows is great, for example, if you’ve exported some data from some other source that you need to analyse. But I’m not so sure that its a good place to keep data that you are adding to, say sales records.
It would be better to keep this sort of data in a database but, if for some reason you need to keep it in a spreadsheet put it in a workbook separate to the one you use to analyse it.
You can then link it back as a data source (look it up).
This is good for a couple of reasons.
One it keeps the overall size of you spreadsheets down and two, you can link it to more than one spreadsheet to perhaps analyse and report on in different ways.
Oh and by the way BACK THEM UP REGULARLY.