Did you notice you knew exactly which file system you used for Windows but didn't tell for Ubuntu? This is usually why this question can't be answered. For most file systems, Windows can't support it. There is FUSE noted at http://en.wikipedia.org/wiki/Filesystem_in_Userspace which is used not only on Linux but MacOSX to solve this issue. For Windows users they have to provide a common ground for exchanging files with Linux.
Hey everyone, my system setup for this question is a Thinkpad T42 with a 40GB hard drive. 30GB is reserved for WinXP my primary OS, therefore it is a NTFS partition. The rest of the drive is partitioned in an extended partition. 6.19GB is partitioned as ext3 and holds Ubuntu, the rest of the drive, 337MB, is reserved as Swap Space.
Now I have GRUB configured to boot Windows as the Primary OS. What I would like to do is access my Ubuntu OS and partition from inside XP. This means full GUI (X System, Nautilus, the whole 9 yards) is this possible?