It depends on what your DVD drive supports. If it's bought quite
some time ago, it might support only DVD-R or DVD+R only. Check
your receipt to see what drive have you bought and buy a DVD that
is compatible with it.
Same for DVD-RW and DVD+RW.
If you have bought it recently, most likely it will be compatible
with both DVD+R and DVD-R. Just double check your receipt to make
sure.
.avi files should open in Windows correctly without the Divx
codecs, if I'm not wrong. Apple Quicktime is also able to open
them.