Is there a need for Power DVD software if I have Nero 7?
Depends what you use them for Stephen. For example one burns, the other doesn't. (As far as I'm aware).
If it was me, and I wasn't struggling for disk space, I'd just keep them both.
If I was short of space, I'd keep the most useful.
I've got a few apps that play DVDs, and between them all, they're much of a muchness. IMHO.