I assume you mean a Duron? The Model 4 Athlon (T-Bird) comes with 256k of L2, on-die, cache. If you are refering to a T-Bird, it is slightly faster, but has some known issues with the KX-133 chipset(KA7). If it is indeed a Duron (128K L2 cache) then you will not even be able to use it with your mobo, it is a Socket "A", not a Slot "A". I personally would stick with the classic, but the T-bird might be a little faster for you. The only thing is that it may not be as stable, or it might be just fine. It is really up to you. If indeed it is a T-Bird, why does someone want to trade it for a "classic" Athlon?