You might have X-Windows (the GUI layer to Linux), usually called by its project name: XFree86, preconfigured for you by Mandrake to switch resolutions really easily. Try:
CTRL ALT +/-
That should toggle your monitor through the various resolutions... If that doesn't work post back and I can walk you through hand hacking it.
Mounting a windows partition is going to be a little more messy. The filesystems for Win95/98/Me was Fat32, incredibly well supported in Linux, so fell in fact that Mandy 8.1 usually creates a mounted directory for you, /etc/fstab entry and all. Since I'm guessing it didn't, you're probably running Win2k or XP. Try this, yeah, from the command line, just open a terminal, xterm, gnome terminal, whatever:
su (enter root's passwrd)
mkdir /mnt/windows (That'll make a place to put all of the windows goop)
mount -t ntfs /dev/hda1 /mnt/windows
This is unfortunately going to mount the windows part a) Read-Only, and B) accesible by root only.
The reasoning is that whereas the old FAT32 system was mostly ripped off anyway and based on standards that the Linux geeks could get to and emulate, the NTFS system is utterly closed, and makes supporting it guesswork.
It is possible to mount the partition read-write, but I wouldn't recommend ever doing that as you might toast the partition. Also, there is a way to do that and have a user be able to access it... search here around the forums and you'll find it.