The original Pro board did not allow Multiplier adjustment. Also the capacitors changed in size and value. The original K7TPro board is a VERY Stable board but the only way to OC on it is by hard modding the processor bridges which involves cutting bridges as well as connecting them.
The Pro 2 board (ATA66) is also a good board although not quite as stable as the Original Pro (even with those huge capacitors). The Pro 2A Sucks if you get one of the many that have "Issues". I'd stay away from the Pro2A till they get the "Issues" worked out.