Performing actions based upon radio button selection

I need to include two payment gateways on my site. One gateway to accept USD while another to accept INR (Indian currency).

I am planning to include two radio buttons ( 1) USD, 2) INR) on my web page . Now based upon the radio button selection, an appropriate payment gateway (image) should be shown.

What is the best way to implement this scenario? (Backend is PHP/MySql)

 

HTML Buttons and Javascript?

Q...

 

Something like this. Untested.

<script type="text/javascript">
function check() {
   obj = document.currency.type;
   value = type.value;

   alert(value + " was selected");
   
   // the below text that is commented is an example of how to show an iframe based on the selection.
   // document.getElementById('frame').innerHTML = "<iframe src='payment.html?type="+value+"' />";
}
</script>

<form name="currency">
<input type="radio" name="type" value="usd" onchange="check" /> USD <input type="radio" name="type" value="INR" onchange="check()" /> INR
</form>

<span id='frame'></span>

Code (markup):

 

@Cozmic; Do we really need iframe for this? Also what will happen in case Javascript is turned off in a browser?

Basically what I am looking for can be seen on this web page https://www.presentermedia.com/ecomm.php?target=registerform&pid=1
I need a similar functionality shown in 3rd category (Payment information)