Excel stores dates and times as serial numbers that represent an offset from a given date (see Epoch (reference date)) rather than as a string that represents the date or time itself. I wrote a routine to calculate those serial numbers given a date/time string which you could probably modify fairly easily to do the opposite conversion: Re: How to insert local time and date to MS-Access database using PERL program. If you do, please post the code. :-)

HTH

Update: don't use the code from my other post - use DateTime::Format::Excel. Thanks, jmcnamara.