OK, I just presented myself at the Virgin Australia counter in Queenstown. As described above, I'd removed my charger and stuffed it in my pocket but left the laptop in the bag, figuring I'd just take it out if the agent had a problem with weight. She did weigh the bag, and when it came out at 9 kg was adamant that the 7 kg allowance included my laptop. Having read CPMaverick's post, I was equally adamant it did not. She finally asked her colleague who indicated she thought I was right and they let me take my bag, which weighed out at 5.5 kg.
Lesson learned.. I just found CPMaverick's info on the Virgin web site and did a screen shot so next time I'll be prepared. And anytime I show up at a check in counter or a gate the laptop will already be removed from the bag. I actually read they have been known to weigh at their lounges too. Reading what RTWFF wrote about the golds and the platinums, I wonder if what they're doing is counterproductive. They may chase some of their best customers off to Qantas. And does this even really help their revenues? If it happens mainly at check in, presumably the customer would just offload into checked baggage.