I'm afraid that this one is going to be ugly. There is no way to do this (that I know of) other than scripting out all your database objects in 2005, then running the create script(s) in 2000. Most of your scripts should work, but there may be some things like synonyms, partitions, CTEs etc... that would blow up. If that's the case you'll have to try to rewrite views, procs, or functions so that they use only valid SQL 2000 syntax. If your 2005 db uses things like partitions or synonyms, you will have a much harder time... There are too many things where this step could go wrong to even list them out.
However, on the positive side of things, the adoption of the newer features in 2005 is still in its infancy so you are not likely to run into too many.
Once that is done you can copy the data from the 2005 database into 2000 using bcp, DTS, or SSIS.
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If most people are not willing to see the difficulty, this is mainly because, consciously or unconsciously, they assume that it will be they who will settle these questions for the others, and because they are convinced of their own capacity to do this. -Friedrich August von Hayek
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