[vox-tech] Easiest way to calculate date in 100 ns increments?

[emily]

I need to be able to convert dates from a human readable format 
(something like YYYYMMDD) to a number in hundred nanosecond intervals 
starting from Jan 1 1601 as 0.

I hope that makes sense. Anyways, for example, 12th Dec 2003 translates 
to 126871488000000000.

Anyone know a nice easy way to do it?

-- Emily