.htaccess rewrite frustrations - ruby-on-rails

Question

I made my website in PHP originally and used parameters for page/product identification.
ex.) http://mysite.com/?pid=my_products&sid=golf_clubs&GTIN=111111111111
I've now moved over to using RoR and I'd like to set up redirects to clean up the urls
http://mysite.com/my_products/golf_clubs/111111111111
I've looked at tutorials and arrived at this:
RewriteRule ^([^/]+)/([^/]+)/([^/]+)$ ?pid=$1&sid=$2&GTIN=$3 [NC]
I've tested a url and it doesn't redirect at all. I've tried putting this in the .htaccess file to debug and chmodded the log folder to 775 but I get a 500 error:
RewriteLog "/home/myaccount/rails_apps/myapp/log/rewrite.log"
RewriteLogLevel 3
As far as rewrite statements in .htaccess goes, this is what I have:
RewriteEngine On
RewriteLog "/home/myaccount/rails_apps/myapp/log/rewrite.log"
RewriteLogLevel 3
RewriteBase /
RewriteCond %{REQUEST_URI} ^/downloads.*
RewriteRule .* - [L]
RewriteRule ^([^/]+)/([^/]+)/([^/]+)$ pid=$1&sid=$2&GTIN=$3 [NC]
RewriteRule ^$ index.html [QSA]
RewriteRule ^([^.]+)$ $1.html [QSA]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)$ dispatch.fcgi [QSA,L]
ErrorDocument 500 "<h2>Application error</h2>Rails application failed to start properly"
* I am on a shared hosting plan with Bluehost (good gawd I wish they'd update to Rails 3 soon)

Answer 1

If I understand you correctly, you have your rule backwards. You want to catch your old URLs and rewrite them to the new format, correct? In that case, you want this:
RewriteRule ^\?pid=(\w+)\&sid=(\w+)\&GTIN=(\w+) /$1/$2/$3 [NC,R=301,L]
Adding a 301 status will tell the user agent (including well-behaved search bots) that your canonical URLs have permanently changed.