Hmm, I've got the same problem as you.
I have got an AVER-TV DVB-T 761 card but I believe the 771 is almost identical.
I found this installation for Linux guide on the Avermedia web site
http://www.avermedia.com/docs/pdffil...or%20Linux.doc
It looks like heavy stuff and I'm no Linux expert. I am however, going to attempt it at some point in the future and I'll share my experiences in this post, unless of course you beat me to it.
Feel free anyone who knows a bit about setting up DVB-T cards for Linux to look through the above document to see if it can all be simplified a bit or if you think anything is missing.