are you trying to access a windows hdd from linux?
in that case just build in NTFS/FAT32/WHATEVER support to your kernel
are you trying to access a windows box from linux across a network?
samba, you can even build smbfs into your kernel and mount windows shares like you would nfs
are you trying to access a linux hdd from windows?
I don't know the names but i've read about a couple downloadable tools to access reiserfs and ext3 from windows
are you trying to access a linux box from windows across a network?
once again. samba.