I thought the t-birds worked with AMD's 751 Northbridge, but not with the VIA KX133 Northbridge.
...and I thought the K7M uses AMD 751...so the Slot A Tbirds should work.
But I've noticed that the price of the slotA athlons are getting much higher than the socketA ones, especially at higher speeds.
(e.g. ~$490 canadian for slotA 1GHz, ~$300 for socketA 1GHz)
The price difference itself might be enough to get a new socketA motherboard!