>For whatever reason, x is still looking for the old driver

could you be a little more specific about this one.
I mean, if you got leftover driver or config files conflicting, you might need to solve that first.

If modprobe agpgart turns this error, kernel 2.4.22's agpgart does not recognize your chipset. If the "internal" agpgart doesn't work either you might still have hope with the kernel's.
Set your XF86Config-4 to "UseInternalAGPGART" "no",
get out of X and remove fglrx,
modprobe -r fglrx
Then try it as suggested
modprobe agpgart agp_try_unsupported=1
If this is succesfull,
modprobe -v fglrx
startx and see if you have accel.

...but if you have any errors referencing nVidia, at any point, you'll have to look into that first.

In harddrake (mandrake's "device manager") under "Videocard", it lists "Radeon RV250 If [Radeon 9000]" and "Radeon R250 [Radeon 9000] (Secondary)". The bus location of the first is 1:0:0, the bus location of the second is 1:0:1. The "secondary" listing is the driver that I installed. I think I need to figure out how to get rid of the first one and make the second one the default to get anywhere. Harddrake doesn't have very many options, but it does have the option to change the basic display settings (resolution, refresh, color depth) and a test option to ensure the new setting will work. With the first listing, it works fine. With the second listing, when I click on "test", it says:

An error occurred: (EE) fglrx(0):
cannot init AGP
Try to change some parameters

That error seems to get back to the AGP issue. If I can actually get to the point of using that driver, I can probably get the agp issue taken care of with the suggestions I've found here, but I can't even get to that point right now.

Once again, i got remind you that you could never get your radoeon work at all if you use internal agp!!!!!!!
For you case, you have to add "mem=nopentium" in your lilo or grub boot loader and "options agpgart agp_try_unsupported=1" in your modules.conf file which was under /etc/ in red hat. Don't know about mandrakes

Got say what i got say, everyone is here to help you. If not listen, you could never get to you goal!

the agpgart agp_try_unsupported=1 option didn't do crap for me, I already tried it. At this point, I'll get the same error trying to start x regardless of whether I'm trying to use internal or external agpgart. I can't even get to the point of having an issue with the agp yet. I'm guessing if I can get rid of mandrake's default driver and re-install the ati driver, I can at least get to the point where I'll need to figure out any agp issues, but I need help getting rid of that driver first.

if you trying to get ride of the alternative driver. i will say it doens't matter. XF86Config makes all the difference.
Tell me what problem are u having now or was agp the first problem you want to get straight of?
it that's it,
checking your kernel if you had support of /dev/agpgart as module(M) not build in(*)!!!!!
Then radeon card support as module(M), not build in(*)!!!
Then see what it says

Hi wanted you to know this worked perfectly for, just following your instructions. Big Thanks!

Important steps are " For the agpgart during figuration, answer no or use external agpgart which was the only you could get your 3D working right.
Then add "/sbin/modprobe agpgart;/sbin/modprobe fglrx" to /etc/rc.local file "

pleasure to help!!!