What jumper did you move, check again, if it was the clear cmos jumper, then
you have to move it back again.
MasterC got a point with the MHz limit, many of the mobo's with 100/133MHz ram
is limited to 1000-1100 MHz cpu's, so it might be some sort of failsafe thing that
it runs at 1000MHz.
The AGP-port is supposed to run at 66MHz(2*pci speed), what is the fsb-ram-pci
speed in your bios, with the new cpu it should be 133-133-33 MHz (or 133-133-33
ratio). If something goes wrong here and you got 1.33 times your pci/agp
frequency, your TNT-card will fail for sure.
One last thing, how big is the powersupply, your new processor eats ca 30 watts
more than the old one, you need something around 300watt and a big cpu-cooler,
to make your machine happy.
If you got some sort of errorcodes on upstart, post them here, they could
enlighten troubleshooting a bit.
I hope this could somehow be useful to you, and you can make it work again