Is a higher priority a smaller number?

If I tell you drinking coffee is "priority one" for me; I am reasonably sure you will assume that is it very important for me to drink coffee. But is it logical to think of a low number as a high priority; or is it simply a cultural bias?

The question occurred while considering a system that requires tasks where fine grained control is needed when adding new tasks. Here we express priority as a number, and things are not so "intuitive" anymore. When you say 'a higher number has a lower priority'; it sounds like an inverted way of thinking.

I would have liked to stick to some standard. But unable to find such a thing I looked around for examples. Thus, I came across MS-Project. Their choice seems to be more logical (albeit less "intuitive" to me): a higher number has a higher priority.

It is easy for me to imagine my tasking system will one day exchange tasks with MS-Project; so I am leaning towards picking the MS-Project way. And thus, adopting their's as a de facto standard.

I also have internationalization needs (like many of us). Am I making the right choice?