I'd use OO when your going to need to call multiple params at different times/different lexical scopes (the creation of a global cgi variable to control when and where you need certain params), something like the code that follows:

use CGI; 
my $cgi = $cgi->new;

sqlstuff();
email_someone();

sub sqlstuff
{
  my @locations = $cgi->param('locations');
  my $sql = q(select * from table where server like '%someserver%' and
+ );
  $sql .= sprintf "(%s)", join " or ", map { location='$_'" } @locatio
+ns;
  #thanks to [blokhead] for the above
  #see below for explaination
  #if needed in existing %IN hash (with assuming other fields)
  $IN{location} = [ @locations ];
  .... do stuff ...
}

sub email_someone
{
  my $someone = $cgi->params('someone');
  .... do emailing stuff here ...
}
[download]

There are other ways to do this, but having seen your whole script this looks like a good stepping point.

As for your actually code Vars returns a hash while param returns an array (or scalar depending on how it's called) so if you use $cgi->Vars you should use $where .= "$_" for values %IN; (if you have multiple locations from checkboxes you want param as Vars will combine locations into a single string)

Update: Replied to CB questions and sql creation explaination:
sprintf "(%s)" : meaning insert string between ()
join " or " : returns a joined string (using delimiter "\sor\s" for inserting
map { location ='$_'"} @locations; : sets location='$location[0]..[$#location] as the array for join to join