I'm not a X guru, so I might probably forget to give some important information there.

The problem is that when I use the nv driver version 2.1.6 my screen is shifted to the right. That means I have a few pixels wide column on the left of the monitor that is the right part of the display. I cannot take a screenshot, it'll probably need a photo or something like that as the screenshot contains the correct picture.

Anyway, after a while trying to figure out what's happening, I tried an older nv driver, 2.1.2 and the problem was not there.
I tracked this to:
commit ec78618d685759a39d386e9929661037b167fe68
Author: Aaron Plattner <aplattner@nvidia.com>
Date:   Tue Jul 10 11:54:33 2007 -0700

    Bug #4686: Fix a minor GeForceFX + flatpanel + video overlay corruption issue.
    
    This change was originally in XFree86 CVS, nv_dac.c version 1.36 but got
    reverted accidentally.



Reverting that patch in 2.1.6 gives me the correct display.


Some information that might be useful:
$ uname -a
Linux macac 2.6.25-rc2-00015-g1309d4e #15 SMP PREEMPT Mon Feb 18 12:02:07 CET 2008 ppc64 PPC970, altivec supported PowerMac7,2 GNU/Linux

0000:f0:10.0 VGA compatible controller: nVidia Corporation NV34 [GeForce FX 5200 Ultra] (rev a1)

X.Org X Server 1.4.0.90
Release Date: 5 September 2007
X Protocol Version 11, Revision 0
Build Operating System: Linux 2.6.24-rc7 ppc64


(--) PCI:*(240:16:0) nVidia Corporation NV34 [GeForce FX 5200 Ultra] rev 161, Mem @ 0x91000000/24, 0x98000000/27, BIOS @ 0x90000000/17



(--) NV(0): Virtual size is 1680x1050 (pitch 1680)
(**) NV(0): *Driver mode "1680x1050": 117.1 MHz, 63.7 kHz, 59.9 Hz
(II) NV(0): Modeline "1680x1050"x59.9  117.13  1680 1744 1776 1840  1050 1053 1056 1062 +hsync +vsync (63.7 kHz)
(**) NV(0):  Driver mode "1680x1050": 119.0 MHz, 64.7 kHz, 59.9 Hz
(II) NV(0): Modeline "1680x1050"x59.9  119.00  1680 1728 1760 1840  1050 1053 1059 1080 +hsync -vsync (64.7 kHz)
(**) NV(0):  Default mode "1600x1024": 106.9 MHz, 64.0 kHz, 60.0 Hz
(II) NV(0): Modeline "1600x1024"x60.0  106.91  1600 1620 1640 1670  1024 1027 1030 1067 -hsync -vsync (64.0 kHz)
(**) NV(0):  Default mode "1400x1050": 122.0 MHz, 64.9 kHz, 60.0 Hz
(II) NV(0): Modeline "1400x1050"x60.0  122.00  1400 1488 1640 1880  1050 1052 1064 1082 +hsync +vsync (64.9 kHz)
(**) NV(0):  Default mode "1280x1024": 108.0 MHz, 64.0 kHz, 60.0 Hz
(II) NV(0): Modeline "1280x1024"x60.0  108.00  1280 1328 1440 1688  1024 1025 1028 1066 +hsync +vsync (64.0 kHz)
(**) NV(0):  Default mode "1280x960": 108.0 MHz, 60.0 kHz, 60.0 Hz
(II) NV(0): Modeline "1280x960"x60.0  108.00  1280 1376 1488 1800  960 961 964 1000 +hsync +vsync (60.0 kHz)
(**) NV(0):  Default mode "1024x768": 65.0 MHz, 48.4 kHz, 60.0 Hz
(II) NV(0): Modeline "1024x768"x60.0   65.00  1024 1048 1184 1344  768 771 777 806 -hsync -vsync (48.4 kHz)
(**) NV(0):  Default mode "800x600": 40.0 MHz, 37.9 kHz, 60.3 Hz
(II) NV(0): Modeline "800x600"x60.3   40.00  800 840 968 1056  600 601 605 628 +hsync +vsync (37.9 kHz)
(**) NV(0):  Default mode "640x480": 25.2 MHz, 31.5 kHz, 59.9 Hz
(II) NV(0): Modeline "640x480"x59.9   25.18  640 656 752 800  480 490 492 525 -hsync -vsync (31.5 kHz)
(**) NV(0): Display dimensions: (430, 270) mm
(**) NV(0): DPI set to (99, 98)


According to xrandr, the resolution I'm using is:
1680x1050      60.0


Please tell me if you need more information.