Dave
Yes plenty of options but not light on the wallet - a decent single box solution with multiple video inputs and a single 'processed' YUV or RGB over Analogue or Digital cable will cost you £500+; the DVDO iScan Ultra or UltraHD (£950) being contenders for your cash (see
http://www.dvdo.com) along with the soon to be released Lumagen VisionDVI (£800); this unit is Digital out only (see
http://www.lumagen.com)
A lower cost option being to convert everything to Analogue YUV: if you have an AV Receiver with YUV switching you can convert the RGB out of your Digibox to YUV using a
JS Technology RGB2YUV converter (£150) and then simply send all of your signals vai yoru AV Reciver as Analogue YUV to the projector over a suitable cable.
If you don't have an AV Receiver with YUV switching you can add in a high quality external YUV (+ Digital audio) switcher to your set up for under £250 (see
http://www.zektor.com).
Best regards
Joe