I have noticed that Report_Load() option is not available for reports on earlier version of MS Access. Is this unique to 2007?

It was a new event in 2007, yes. Prior versions didn't have that one.

Then my next question is this. I you are using earlier version, how can I assign value to ubound field in a Report at start up.

The value for these field would come from a form.

I typically assign values to controls in the format event of the section containing the control.