The A7V133 use the kt133A chipset, an improved version of the kt133 found in the A7V. The main difference is that it support FSB up to 133 MHz, for Athlon Thunderbird "c" core or Athlon XP with fsb that are 133MHz or 266DDR.
The memory controller was improved on the kt133a as well as it was coupled with a better southbridge, IIRC. I would choose the A7V133 as it will support "faster" cpu, if you manage to find one real cheap.