If the boots are comfy then just start replacing one thing at a time as money allows. The first thing I would do if I was you is get not a "new" board but one that's sized properly for you. For your weight that 160 is a bit large. That will make your life on the mountain drastically better. After that get some nice responsive bindings.
If you can get that DC for $90 and it's in good shape I think that board would suit you well (only going by size, not sure what your riding style is). It'll be a lot easier to throw turns etc. with the shorter board.