Onclick & Ie The not so new standards problem

[DoR 0]

I want to do some action when I click on a paragraph (for example).
Here is the code:

...<script>function refresh_data(){alert ('test');}</script><p onClick='refresh_data();'>Refresh</p>...

This works perfect on Firefox and on IE 6.0 and greater.
The fact is, it doesn't work on IE 5.0. What should I do? Re-design everything to allow all kind of browsers (including those not so old and much used like IE5.0) or recommend users to upgrade their borwsers?.

On an Intranet service I can limit the design to some browsers but when it is a commercial and public application, I can't be loosing clients!!.

What do you say?
Is so difficult to use standars?
What's your experience?

Here is an interesting discussion.

[Inspiron 0]

Its not your fault...That's the reason why Microsoft released IE 6.0IE 5 is not compatible to that code...Anyway, IE 5 I don't think there's much people using it already...So the problem issn't big..