Form/Loop question

Question about handling data from a form.. I have a form which includes lots of checkboxes for people to select multiple items. Is there an easy way to grab that data and find out which were selected? I have the checkboxes named in such a way that each column of related options start with a "1_" or "2_" etc. It sounds like I can use radio buttons and just let people select more than one but I'm not sure that'd be easier to read from. Can I read them into an array somehow??

Also, someone here posted the following code

foreach($HTTP_POST_VARS as $key=>$value)
{
    ${$key} = $value;
}

to grab everything from a form into a variable of the same name, but that gives me a parser error (listed as the line before it starts). :(

Any help is greatly appreciated!