Wendy,
Some of the low-cost airlines may have changed by now but I flew from Rome to Nice for a cruise a few years ago. I took virgin express. We had to change airplane in Brussels but it was a breeze. More importanly, they didn't charge us anything extra for our luggage. On the same trip we then flew from Nice to London on Easyjet without problems. Next we flew from London to Glasgow on Ryanair and they tried to charge us eighty pounds each for our one suitcase each being over the limit. We negoitiated down to forty pounds each. Considering we got the tickets for one pence each on a sale on their website, it wasn't the end of the world.