My macbook (mid 2008) mini display port is bigger than the new mini display port plug, is there an adapter to get?

Trying to plug my 30" Cinema Display (late 2008) into my macbook and imac with this adapter, but the mini display port plug (male) is much smaller than the ports on my computers. Is there an adapter for the 2 sizes to work? Or did I just waist $100 on a plug I can't use?

Mini DisplayPort to Dual-Link DVI Adapter

Mini DisplayPort to Dual-Link DVI Adapter

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