I read today on Lifehacker about a freeware tool called Linux Reader. It provides you with read access to ext2/ext3 partitions within Windows and has an explorer-like interface that allows you to drag and drop files from a standard Linux partition.
What about full read/write access? With a little googling, I found another freeware utility called Ext2 IFS that provides full write access. It’s is essentially a kernel ext2/ext3 filesystem driver for Windows, which allows the operating system to access your Linux partitions in a more native manner.
After installing, you can mount your Linux partition under a drive letter, just like you would an NTFS partition. The drive will be available in Explorer and within any file browser dialog in your favorite Windows applications.
As far as I can tell, both packages pretty much ignore the permission settings on files, so you’ll have full access to files across the entire partition. One caveat is that LVM volumes are not supported by the Ext2 IFS driver (and I’m assuming the same is true for Linux Reader). ReiserFS, XFS and other filesystems are also not supported. For your plain Jane dual-boot system with an ext3 partition, however, you should have no problem accessing your Linux files from within Windows.