URGENT! Mulitbox problem!!

Hello everyone,
I have a problem with multibox operations in my form.So please help me as soon as possible. Any help in this regard is greatly appreciated.

I have a form with rows generated dynamically. for every row there is a checkbox and two text boxes associated with it. checkbox, textbox1, textbox2 are defines as arrays in actionform and I am getting the values in action class. I am using Struts Multibox to display the checkbox.

At the beginning when the form is displayed all the checkboxes are not checked (unchecked) and I want all the text boxes to be disabled.
upto this point I am getting the result.<html:text property="Amount" size="10" disabled="true"/>
There is a save button in this form which saves the rows for which the checkbox is checked and textboxes are entered with values.
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I am having difficulty doing these!
Q1) when the user clicks the checkbox , the textboxes associated with that checkbox ( that is same row) should be enabled to enter some data.
If the user clicks 2, 5, 6 checkboxes only textboxes for those rows should be enabled. if the user does not enter data in text boxes and tries to save it, it needs to pop up a message to enter data in the textbox
first before saving.

for this I am thinking of calling _javascript function in the <html:multibox property="saveselections" onfiltered="enabledTextFields()">

First of all is this approach right? how to write this in _javascript?

Q2) what is the best approach to define the type of the text box in actionform when amount (ex $10,000.00) needs to be entered.
In action class I need to convert to BigDecimal. so can I define it as BigDecimal in actionform itself?

Thank you for your help!!

Thilothama.