Project Thunderbird (overclocking a 1.0GHz T-Bird)

My mom has an aging Micron Milinia with the following specs and a freshly expired extended warranty:
1.0 GHz T-Bird
-Aurora - Gigabyte 7DX mobo (copied from mfg website)
-128MB PC2000 DDR
-256MB PC2100 DDR (not stock)
-Geforce 4 MX440 (mine, and in danger of being removed and replace with a 32MB TNT 2 because i might want the card for a second system)
-Modem
-Onboard sound

The Plan:
-Replace 128MB stick of ram with second 256MB stick of PC2100
-Overclock to a maximum FSB of 133MHz (x2)
-Replace cheep generic Delta DC Brushless 92mm exhaust and and 92mm intake and filter intake because PSU will lead to slight negative pressure.
-Put on a real HSF instead of the dinky crap on there now.

Here is where i need help.
The mobo should be capable of running at 266MHz.
Is the proc likely to be capable of hitting this speed?
Lastly, how will performance be affected by an underclocked PCI and AGP bus? Im not sure how this motherboard will overclock, it might just be setting the FSB higher and trying to boot (i dont know about the incrimentals on the FSB). I cant find the mobo on gigabyte's website. I either will need to flip a jumper or get a new bios. I dont know much about overclocking this thing and my inability to find the mobo on the mfg website is confusing me.

EDIT: I found the mobo on the Gigabyte website and it is supposed to support any 266 fsb chip. But the bios to do that sais its only for Revission 3. I have decided my a priori burdon (sorry for latin, primary burdon) is to get a real bios in there and try to figure out what the computer will support. I need help finidng the revission number of the motherboard itself. It may be on the mobo PCB but im not sure where. CPU-Z does not give me a revission. Im going to check the pcb for the revission, ill update if i find it.

EDIT: Mobo is Revission 2.2 so i guess the 2600+ is a nogo, 2200+ is still an option.

Is 'GA-7DXE' the exact model # of your motherboard? If it is, that motherboard has the AMD 761 chipset which doesn't overclock very well. I had an Abit KG7 which has the same chipset and the best I was able to overclock the fsb to was 150MHz using PC2400 RAM. I don't know if the motherboard supports multiplier changes, but you might be able to get a higher overclock by changing the multiplier. The Thunderbird is multiplier locked by default, but it can be easily unlocked by doing this 'pencil trick'. Also, check the stepping code of the Thunderbird cpu. It can be found on the cpu core. If the first four letters begin with 'AXIA' it can overclock pretty well. Good luck.