Downscaling to alternate display

[BerMM]

I plan to build a dedicated DVR this spring, and until then I'm adapting my gaming cube to multitask as one. I really want to mirror my usual 1080p output to my old, but barely used, 800x600 projector as an alternate display. Obviously I need to find some sort of adapter that will downscale to a signal the projector can handle. The projector specs are here, and this is the only solution I've found. Is this advised? How will it affect HDCP? Is there another solution I'm missing?

Thanks!