There are free alternatives for both sides of access to either Windows and Mac OS X.
For accessing an HFS+ formatted volume under Windows you could use HFS Explorer
It's a standalone progamme that works with Java. With it you can browse your HFS+ formatted volumes.
MacDrive is of course simpler, because you can just open the Explorer and there is your HFS+ volume, shown like all the other volumes.
For writing to an NTFS formatted volume under Mac OS x you can use MacFuse and the NTFS 3G Read/Write driver
. It works like a charm for me.