this one worked for me after about 45 minutes of playing around with suggested scripts

<IfModule mod_rewrite.c>
RewriteEngine on

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule .+ - [L]
RewriteRule ^([A-Za-z0-9_-]+)$ http://www.yoursite.com/profile.php?ID=$1 [QSA,L]
</IfModule>