InfoPath Dev

 I'd like to have a form which allows the form filler to maintain a running tally (tally does not require outside data as it starts at 0 when the form is opened)

The user will essentially be keeping track of certain events and tally them accordingly.

Basically the functionality I want is identical to a NumericUpDown Class from .NET

example:

http://www.asp.net/ajax/ajaxcontroltoolkit/Samples/NumericUpDown/NumericUpDown.aspx

Do I have to use buttons and code in the background to create this or is there a better way to do this in InfoPath 2007 (web compatible mode) ?

You don't need any code to accomplish this.  Just add a textbox to your form, add one button with a rule to increase that textbox's field by 1, and another button with a rule to decrease the field's value by 1.  All set!