I couldn't get my custom settings to "stick" after reboot either. Try installing the 180.48 drivers for Vista and see if that fixes it. The new 181.22 drivers seem to be buggy with Vista. Here is the problem I was experiencing that I posted a couple days ago: http://www.tomshardware.com/forum/259845-33-geforce-dri...
Thanks for your suggestion. And I discovered what was causing my problem. I have a 2-way DVI-to-DVI KVM, and when the KVM was switched to the other PC during the subject PC's booting process, I realized after lots of trial and error that that was when the problem would occur. After researching more, what I found is that with many LCD monitors and with many modern video cards, the monitor DDC information is not retained unless the monitor is electrically connected during boot up. So my video card didn't know what kind of monitor it was supposed to be adjusting for, and the resolution would thus revert to the default 1024x768. Once I realized the problem and began booting only when the KVM was switched to that PC, the "problem" went away.
During my research, I also discovered that there is actually a device available to bypass this problem. It is called a "DVI-D DDC Ghost" and is a little box that connects between the PC video card and the KVM switch. When the KVM is switched to the other PC, this little box retains the DDC information and provides it to the video card. However, at about $50-$60, it isn't for everyone.
It would be nice if someone knows and could share a way to accomplish this without the addition of more hardware!