How can I access a Linux partition from Windows?

Cooperative Linux is the first working free and open source method for optimally running Linux on Microsoft Windows natively. More generally, Cooperative Linux (short-named coLinux) is a port of the Linux kernel that allows it to run cooperatively alongside another operating system on a single machine. For instance, it allows one to freely run Linux on Windows 2000/XP/Vista/7.

here's a tutorial: Ext3, ReiserFS & XFS in Windows thanks to coLinux

After some investigation, I decided to use VirtualBox as I trusted it a bit more than Cooperative Linux. Here's the super-short guide to getting VirtualBox setup to access raw partitions using your current install of Linux. With only minor modifications, you can create a new VM that access existing physical partitions:

(1) Create a virtual disk that's nothing more than a reference to your existing file systems using VBoxManage:

# Note, backslashes immediately before new lines are continuations
C:\>cd \users\kpederson\.virtualbox\harddisks
C:\Users\kpederson\.VirtualBox\HardDisks>"\Program Files\Oracle\VirtualBox\VBoxManage" \
  internalcommands createrawvmdk -filename rawdisk.vmdk -rawdisk \\.\PhysicalDrive0 \
  -partitions 5,6,7,8 -mbr f:\sda5_mbr -register

(2) Create a virtual machine that uses the virtual disk created in step 1. In the above command I called it rawdisk.vmdk.

(3) Configure your virtual machine using VirtualBox's bridged networking. In my case, I found it buggy, so I setup my virtual machine to use host-only networking and then used Windows to bridge the host-only network adapter with my real (i.e. physical) network adapter.

(4) Configure a share in samba:

[shared]
   comment = Shared Documents
   path = /home/shared
   guest ok = no
   writable = yes

And with samba up and running, I had access to all the files I needed. In addition, I can use ssh/sftp to access all the files using WinSCP or a similar file-transfer client.

Full details are available on a blog post I wrote entitled "Accessing Linux File Systems from within Windows"