Conditional Redirect with sidebar form while keeping field data

Hi,
I've been trying to get a teaser form to redirect to different forms based on selection while retaining field data. I've been using these two forum posts as guides:

http://www.gravityhelp.com/forums/topic/terms-of-conditions#post-7442
and
http://www.gravityhelp.com/forums/topic/conditional-redirects-preserving-posted-data

I was able to get it to redirect properly, but can't seem to work out keeping the field data. Here's the scenario:

A teaser form has two fields. A radio button for Buy/Sell/BuyandSell and a drop down list of the state they are looking for. The radio button selection directs you to what form you will fill out and I want to retain the State in the new form you are sent to. The redirect code looks like

$agree == $_GET['BuySell'];
switch ($agree)
	    {

	        case "Buy a Home":
	        // if buy redirect to the following page
	        header("Location: WEBSITE_URL_1");
	        break;

	        case "Sell a Home":
	        // if sell redirect to the following page
	        header("Location: WEBSITE_URL_2");
	        break;

			case "BuySellHome":
	        // if buy and sell redirect to the following page
	        header("Location: WEBSITE_URL_3");
	        break;

	    }

but couldn't incorporate either of the methods from the second post successfully. Any help at all would be greatly appreciated. Thanks!

Thank you for the quick response! I still seem to be having an issue though. I'm receiving this error when I submit the form:

Parse error: syntax error, unexpected T_LNUMBER in /home/tmueller/public_html/rebateagents.net/wp-content/themes/theme1411/page-formsplash.php on line 10

Just to see the whole block, here's lines 8-11

case "Buy a Home":
	        // if buy redirect to the following page
	        header('Location: http://www.rebateagents.net/buy-form/?State=$lead'2'');
	        break;

?State is the parameter name of the field I want to preserve and $lead['2'] is it's ID, correct?

Also, if it's any help Dreamweaver code syntax flagged the single quotes surrounding 2 as an issue. Just to restate my goals, one field (Buy/Sell/Buy and Sell) is dictating which redirect to use and the only information I want carried over to the next form is which State they select in a drop down. Thanks again!