I have tried the following without success
WHERE orderdate >= '31/10/2010'
Any error returned?
Anyway, whenever you are using date strings, make sure they are in non-locale dependent format. Best is ISO: YYYY-MM-DD (YYYYMMDD will also work) , or you can use words for month: '31 Oct 2010'
so:
WHERE orderdate >= '20101031'
or
WHERE orderdate >= '31 Oct 2010'