Isko, sorry for not replying earlier. But it was midnight in my part of the world...
Trimai's advise is good, provided you know how to do the wire mod to unlock the cpu. If not, you may not want to risk it as there is always a chance that you could burn out your cpu.
Your best bet would be a 2100XP Tbred-B. I am not sure as to why your mobo will not boot with the 2200XP as theoretically, it should without modifications. Hence, I'm a little hesitant to advise you to get it.
I have also reviewed your actions so far from this thread. That you have flashed the new bios (you may need to do this again) but with OC Master's version which I find to be quite stable. It could have been a bad flash that prevents your mobo from posting.
Maybe you could borrow a friend's T'bird (though I can imagine that this will be difficult) 2100XP-B or 2400XP-B to try. Review all the necessary steps again to prepare your mobo.
a) Reflash bios (be careful)
b) Clean up mobo. I have found that dust in the ram slots, or agp slots can be very upsetting.
c) Install your old cpu with a minimal set of components i.e. graphics card, floppy drive, hdd drive, one stick of ram only...and of course the keyboard and mouse.
d) Test that everything is working properly.
e) Reinstall a T-bird 2100XP - 2400XP type B.
f) Reboot.
You should have a boot-up that says "Unknown CPU at 2000 mhz" and an error message "Unknown CPU may not be usable. Press del to enter setup".
Doing this procedure will ensure that it is not another component, eg. ram, that is preventing boot-up. I would suggest that you REALLY make sure that your ram is not causing problems. Ram that is unstable may run with a slower CPU, but the moment you up the speed, they stop working. This, I have also experienced. My ram used to run at 148, Cas 2 stable (and they were cheap PC-133 Infenion ram blocks) at an ambient temp of 33 degrees, so you can imagine how hot they got. When they finally got unmanageable, I changed them, and still keep them as a reminder....every chip has a nice heat pattern on them...perfect examples of how overclocking can destroy your ram...
If you succeed, then install other components one by one to find the guilty component.
When you get to the stage of successful boot, post in this forum again. I check in several times a day, so I will reply usually almost immediately.