The supplied driver level for the Tulip driver does not work properly with the SMC 8432T Etherpower. You get link beat timeout, the driver then tries to change to 10base2 but there is no 10base2 port and the wire to the hub is in the 10baseT port. I've been through this with the developer, Donald Becker. His latest test version 0.91c fixes the link beat problem but the card still goes offline every few seconds -- you just don't lose the outgoing packets when it does. SMC Etherpower is listed as a Tier 1 supported card on your website. Donald Becker is responsible for too many drivers at once. You need to give him help and in the meantime remove SMC from the supported list or post a warning. I purchased RH5.2, not using the freebie download.
We do not currently have an SMC 8432T card in the test lab and should probably get one to help replicate this problem. We do although have a 8432BT which is a PCI 10Mbps 10baseT Etherpower card. I do not know if there are any differences between the two but the one we have works fine with both 5.2 and 6.0. That is probably the model that the hardware compatibility list is referring to.