If you want to keep a variable to track whether the module is loaded you should use our, as you should always use strict (and warnings).

use strict;
use warnings;
our $lwpavailable = 0;

BEGIN { 
   eval ("
      use LWP::UserAgent;
      use HTTP::Request::Common;
   ");
   
   if ($@) {
      $lwpavailable = 0;
   } else {
      $lwpavailable = 1;
   }
}
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well, I have a package that has a few separate programs, and I want the variables to be shared by all of them. I use my for local variables, but the variables that i want shared i just dont declare... i tried to use our on them, but it had unintended consequences that I couldn't figure out...

I also tried to use use vars qw($name) but that didnt work either...

is there a significant amount of processing that is requires to load these modules? if the script is accessed, say, several 1000 times per day, attempting to load the modules in the beginning might bog things down more than, say, if they were loaded in the middle of the script only when they are needed (which is infrequent)?

I ran

perl -le "use Time::HiRes qw( time ); $t1=time; eval 'use LWP::UserAge
+nt; use HTTP::Request::Common;'; $t2=time; print $t2-$t1"
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a couple of times, and got

0.0728998184204102
0.0660429000854492
0.0670039653778076
0.0661859512329102
[download]

That means you'd save at most 70ms every time the script is run. I've waited longer than the time you'd save per day for a single PerlMonks page to load :) If you're that desperate for speed, you should switch to mod_perl, FastCGI, or similar