Thankyou for your help :) I found a oneliner that doesn't do the whole job but still
$lines =~ s/<(.+?)>/'<'.uc($1).'>'/ge;
This will convert src attributes such as blah.gif to uppercase which would wreak havock on some servers but its only an exercise to drive me nuts :) Else I could:

if ($lines=~m/(<)(.+)(>)/)
    {
                            $tag=$1;
                            $tag2=$2;
                            $tag3=$3;
                            $tag2=~tr/a-z/A-Z/;
                            $new=$tag.$tag2.$tag3;
    }                        
    $upper=~s/(<)(.+)(>)/$new/g;
[download]

Boy am I hangin to learn about modules now :)