First if some would like Nero to work good for them - There are native alternatives to most things crossover runs, if people want to use a program they like under crossover that is their choice.
The programs that may provide some of the functionality under Linux include :-
Video-DVDrip - Rips and encodes DVD to SVCD/VCD - has quite a lot of dependencies but works fine - You will need DVD programs / libraries that may not come as part of your Distro due to patents etc - Under SuSE most of the info you need can be found at http://packman.links2linux.de/ - most other distros have similar places to get packages for example plf for Mandrake.
Best answer for DVD backup is to use dvdbackup ( dvdbackup -M -i/dev/dvd -o / ) then use DVD shrink under crossover to open this and resize the DVD, with output saved as an ISO and then burnt with K3B.
As you can see a bit long winded but it works