Need a Digital Converter Box... Recommendations?

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I have two $40 coupons and even though I have Digital cable and 32" CRT and a couple of smaller CRT's I would like to get a Digital Converter Box or two "Just In Case" I tell the cable company to take a hike. Can anyone recommend "WHICH" converter box is the best bang for the buck? I'd like to keep them as close to $40 if possible.

Thanks.
Bill