The 7D footage is going to look 10x better than your SD footage, especially if the person who shot it had a lens better than the normal 18-55 is kit lens. So my suggestion is edit just the 7D footage by itself, make a complete edit out of it and then go back to your SD footage and convert everything to one codec and format.
720 x 480
DV/DVCPRO-NTSC
23.98 (assuming they shot in this, if not, convert it to it)
Consider using the 7D footage for DVD and using the SD footage for a short 3min web version? Letter box it too.
I set up some videos for brides in the past and whenever I post something online a couple weeks after a wedding, my website sky rockets in hits. Brides love to see their special day online, and they especially love to send out emails with a link to the vid. so their co-workers can see what they missed out on.
michaelstringfield.com
stringfieldphotography.com