It IS possible to use samba to browse your NTFS drives / partitions. At this stage NTFS is read only though (at least without a great deal of risk). If you can convince M$ to hand over the specs of their NTFS then it may become writeable too!
I've messed around with a lot of my settings trying to get samba to share my mounted NTFS drive.... so I'm not sure how important the earlier changes I made were.
The problem is not with samba for a start - if you can access other shares then obviously you're already in.
Initially I thought the mount permissions were the problem so tried the following:
mount -t ntfs /dev/hdb1 /media/WinXP -o ro,users,owner,umask=0222
I'm not sure if Ubuntu already has ntfs installed. My distro is Fedora Core 4, so I had to download the file system myself. The options above make the mount r-xr-xr-x.
To the crux of the matter: Does Ubuntu run SELinux?
If so, then it's probably blocking some aspect of smbd or nmbd for sharing the mount point. I set my SELinux to Permissive and it all worked!!
You'd still need to boot to WinXP to move / change files though.