Stopping Google indexing incorrect versions of my home page

[befuddle]

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I need some help with .htaccess or equivalent. What's the most efficient way of stopping Google indexing my home page with these appended parameters?

www.shopcodes.co.uk/?product=burberry
www.shopcodes.co.uk/?product=calvin_klein
www.shopcodes.co.uk/?product=prada

If you do searches and my site appears, often the three urls above appear. I don't want the above indexed as they are currently but I obviously want it to index

www.shopcodes.co.uk

Google is sometimes returning these two urls below as first and second listings but the pages are exactly the same.

www.shopcodes.co.uk
www.shopcodes.co.uk/?product=prada

The "product" urls are a hangover of when a site I once owned redirected to Shop Codes. There's a site still linking to those pages with the "?product" parameters in but removing all those links would be a painful process.

So I am looking for a safe .htaccess or robots.txt solution that won't harm the indexing of the 'real' homepage.

[tbp]

Disallow: /?product=*

Think that would work, test it in google sitemaps though

[morleymouse]

if its a script that handles the ?product= part which I imagine it will be tell google that its moved something (in php) like...

if ($product) {
Header( "HTTP/1.1 301 Moved Permanently" );
Header( "Location: http://www.shopcodes.co.uk" );
} 

at the very top of the index / default page, then if you go to http://www.shopcodes.co.uk?product=anything it should do a 301 permanent redirect to the main page, google should then eventually forget about the ?product URL's rather than just ignorning them whilever the robots file is there

[befuddle]

Thanks tbp and Dan. I've implemented both.

Cheers,
Ray