I would stick with the Singer for now and save up for a better quality new sewing machine. Many of the low-end new machines have a small harp size (area under the arm where the bulk of a quilt needs to be while machine quilting) and do not handle thicknesses well. In these respects, your old Singer is likely to perform much better.
A new low-end machine will have the convenience of a needle-down setting (not a necessity until you get used to the feature!) and some fancy embroidery stitches (not necessary for quilting). If you save up for a Janome 1500 or 1600P (probably around $1,000 or so in the near future) you will get a heavy-duty machine with all the conveniences, a large harp for machine quilting, tons of embroidery stitches, and something that will last many decades.