http://www.fs-driver.org/faq.html#not_sup_feat
"The current version of the Ext2 file system driver does not
maintain access rights. All users can access all the Ext2
volumes that a drive letter is created for. For example, if
a drive letter has been created for an Ext2 volume, which is
the root volume of a Linux installation, you can simply read
and modify files such as /etc/passwd and /etc/shadow. User
names are readable and passwords of these users can be quite
easily cracked and modified!"
SH: Perhaps your situation is also dangerous, I don't know,
are you the sole user? The program below is designed to do
what you are thinking of doing now, making Linux read only.
http://www.diskinternals.com/linux-reader/
"How to get safe and quick access to alternative file systems?
DiskInternals Linux Reader is a new easy way to do this. This
program plays the role of a bridge between your Windows and
Ext2/Ext3 Linux file systems. This easy-to-use tool runs under
Windows and allows you to browse Ext2/Ext3 Linux file systems
and extract files from there.
There are a number of evident merits of the program, which
you should know. First of all, DiskInternals Linux Reader is
absolutely free. Secondly, the program provides for read-only
access and *does not allow you to make records* in Ext2/Ext3
file system partitions. This guarantees that the interference
in an alternative file system
will not affect the work of Linux later.
Apart from this, it is necessary to note, that it gives you an
opportunity to use common Windows Explorer for extracting data.
A preview option for pictures is one more pleasant point, which
is worth mentioning."
SH: I will download this, experiment and let you know the results.