How to make my ubuntu drive usable in Windows

[BigBear]

I have two hard drives in my computer, one has Windows Vista installed, the other has Ubuntu installed. My computer auto logs into Windows Vista but I can access Ubuntu from the boot menu. I want to uninstall Ubuntu so that in Windows Vista I can access and use the hard drive that Ubuntu is using.

In 'Computer' I cannot see the drive with Ubuntu installed, but through Ubuntu I can see both drives.

[DemonWasp]

You almost certainly have the following setup (but feel free to correct me if I'm wrong):

Windows Drive: NTFS file system; bootable. Hosts the boot loader (GRUB, installed by Ubuntu) and Vista operating system and all your Windows files.
Ubuntu Drive: ext3/ext4/reiserfs file system; not bootable. Hosts the Ubuntu operating system and your Ubuntu files.

The reason that Vista can't "see" the Ubuntu drive is that it doesn't understand ext3 or ext4 or reiserfs. In fact, Windows only really understands a few file systems (FAT and variants, NTFS (most common) and the various CD/DVD/BluRay formats). Ubuntu helpfully understands all of those and dozens of other, superior filesystems (which it generally uses when it installs itself), so it sees both drives.

To "share", you will have to use something both operating systems understand, usually NTFS. However, there's a catch: Ubuntu can't boot off of an NTFS partition (at least, it wasn't able to last time I checked; something about "user-space drivers"). This means your setup will have to have at least 3 partitions:

A) NTFS. Hosts Windows Vista + files. Readable by both operating systems.
B) NTFS. Hosts shared files. On a different disk from (A). Readable by both operating systems.
C) ext4. Hosts Ubuntu (including /home). Only readable by Ubuntu. ~20GB.

Getting to this configuration without reformatting or repartitioning is possible, but tricky. Re-partitioning is more straightforward, but requires a full reinstall of your Ubuntu operating system, and requires that you remove any files you want to keep from that disk. Read about GParted; it's great for handling this type of operation.

[BigBear]

I don't know which file system Ubunut is using but that makes sense.

Also there is no partition because they are actually two physical drives.

I would like to format the Ubuntu drive and just use it with NTFS with Windows Vista

[DemonWasp]

Even though you "just have two physical drives", they still use the partitioning mechanism. Both still have a partition table (thing that tells the computer where the partitions are) and both still have partitions: they just have one large partition each.

If you intend to wipe out Ubuntu entirely (including deleting all files stored on that drive), then there are tools within Windows to let you reformat a drive it doesn't otherwise "see" (when a drive appears in Windows Explorer, it is "mounted"; when it cannot be mounted, Windows still knows its there, but doesn't display it to avoid confusing non-power users). See here: http://windows.microsoft.com/en-CA/windows-vista/Create-and-format-a-hard-disk-partition

If you intend to keep Ubuntu around, you will have to do a bit more work, though it should be possible to share most of the space between both operating systems.