Scans? NEW to burning

Ok i am looking at getting a dvd burner the best money can buy. Currently looking at these:

Pioneer DVR-610
BenQ DW1640
NEC nd-4551

Basicly i want to make back-ups of my dvds and xbox games. I want quality first and then speed next. I read lots of people that talk about scans and i am not sure what they are speaking of. Is there an article that talks about what a quality dvd burner should do? Thanks for the info also if there are any better burners out there or comming soon i would not mind info on them. Thanks in advance. Brian

Not sure if importante but my system specs are as follows:

Athlon 64 X2 4400+
A8N32-SLI Deluxe
2gig memory
2 74gb Raptors Raid 0
2 500gb Hitachi’s Raid 1
one 7800gt for now