samba doesn't change modification dates?

I have a windows share (fat32) mounted on my linux box with samba. If
I change a text file on the linux side and save it, the modification
date of the file is updated on the linux side. But, if I change the
file on the windows side, the modification date doesn't change on the
linux side.

The file DOES change, it has the new text I saved into it on the
windows side, but the modification date doesn't change.

Can I configure samba to make it get this right? This is messing up
subversion, which doesn't think the file has changed since the mod
date hasn't. (remember fat32 *does* have modification dates!!)

I looked at dosfiletimes=true, but that doesn't apply here because I'm
mounting an xp partition on the linux side, not the inverse.

$ /usr/sbin/smbd -V
Version 3.0.23c-2