Is there software that will convert a jpg to a vector format?
Vector Magic
Convert bitmap images like JPEGs, GIFs and PNGs to the crisp, clean, scalable vector art of EPS, SVG, and PDF with the world's best auto-tracing software.
Inkscape (a nice free-software vector drawing software) has built-in tracing capabilities.
Just import a bitmap (File/Import Bitmap...), the choose Path/Trace Bitmap. I've used it successfully to trace an image for printing on T-Shirts.