Sigh...I'm going to be the contrarian here...sorry. I hate sergers...with a passion. I used to have a swimwear company and I would have to make the first samples with them. I had 2 domestic sergers and both of them gave me nothing but headaches. I think that they were both Baby Locks, but I can't be certain. They each had 4 spools of thread and very complicated threading systems. Things were always going wrong and I would have to re-thread them all the time. It was a nightmare. My contractors said the same thing about both, their domestic and commercial sergers. They had a guy on the floor who's only job was to walk around and come over to each problem machine and fix it until it went crazy again. It went on all day like that. (He had the patience of a saint.)
To answer your question, no, you don't need a serger to quilt. A straight stitch machine is all you really need, unless you want to get fancy with embellished stitching.
~ C