"Video-
My screen resolution is will not go any higher than 800x600 73Hz... I have an nvidia AGP card, so I know it can get better than that. I tried changing the driver in /etc/X11/XF86Config-4 from vesa to nvidia, thinking it may be that easy, but that just crashed my X on reboot.
So, I changed it back."
Because it's not configured correctly, you don't explain what you did. Did you let it autodetect during the installation? Did you do it manually? Did you typed your card's memory amount, your monitor's horizontal and vertical frequencies? Did you choose the correct resolution from the list given? It seems to me your problem is lack of knowledge when installing.
Read sections 9 and 10
The Very Verbose Debian Installation Walkthrough
http://osnews.com/story.php?news_id=2016
it will guide you step by step in the process of configurating X. Then do:
#dpkg-reconfigure xserver-xfree86
and this time, if you did your homework, it will be fine.
Without this working correctly, no kernel is gonna function right, you're just dragging the problems from one kernel to another. Fix this ASAP, and do not advanced until it's fixed.
Sound
"I am using Gnome for my desktop, and the volume applet doesn't work. When I try to adjust it, as soon as I let go of the mouse,"
It seems you have a problem with Gnome, I don't use it, maybe somebody who uses Gnome can help you. You can try the Gnome channel (#gnome) at the IRC on the Freenode server with Xchat.
Kernel:
"I got through to the upgrade Kernel part of the thread, and followed those instuctions to the "T". I picked kernel 2.6.8-1-k7, because I am running on a KT-133AK7 mobo with a AMD 1200 processor."
After fixing the X-Configuration with dpkg-reconfigure xserver-xfree86,
Run debfoster and get rid of the kernel 2.6, make sure you have the right name (k-6 or 7) .
Assuming you're correct about the k7 part, this time try this one:
# apt-get install kernel-image-2.6-k7
(- Linux kernel image for version 2.6 on AMD K7)
maybe this time, it will work for you
#update-grub
#reboot