Beagle - 4:55 pm on Jan 7, 2006 (gmt 0) I'm assuming the "before shopping" in the thread title was a mis-type?
Tell them what the advantages are to registering (ability to use wish list, no need to re-enter info, etc.), but let them make the choice whether to do it or not. I think if you look at the serious sites you're talking about, you'll see that most of them make it an option. If the customer does decide to register, it's also common to give the option of storing or not storing credit card information as part of the process.
I'm assuming the "before shopping" in the thread title was a mis-type?