In single-user mode, the filesystem is mounted read-only so that you can 
fsck it with little likelihood of causing filesystem damage.  If you 
really want to mount it read-write in single user mode, you can 

mount -w /

which will mount the root filesystem read-write.  If you have other 
filesystems, you need to give the proper device to the mount command.

X will not run in single-user mode to the best of my knowledge, because I 
don't think that the necessary daemons to manage the port connections it 
must have to run have been started at that point.  You need to exit from 
single-user mode (type exit or hit Ctrl-D), which will then run /etc/rc*, 
mount the listed filesystems read-write (or whatever you happen to 
specify), and then put you into multi-user mode from which you can run X.

Later.

-- 
Colin Wood                                      ender@is.rice.edu
Consultant                                        Rice University
Information Technology Services                       Houston, TX