I just don't understand your :

system("cat /proc/loadavg");
while (<STDIN>) {
[download]

why not just :

while (</proc/loadavg>) {
[download]

UPDATE :
Furthermore if it returns only one line (as I suspect) on all platforms, the loop is useless...

Anyway rob_au pointed us to the right direction today with his post about Proc::ProcessTable

"Only Bad Coders Code Badly In Perl" (OBC2BIP)