I have heard only negative reports for the Dell-branded 3CCFE575CT cards. Since these are all being used on Dell laptops, I don't know if the problem is a bad interaction with the Linux socket drivers and the Dell systems, or a problem with the 3c575_cb driver. 3Com says that the Dell-branded cards are identical to the 3CCFE575CT cards they sell under their own name. I have several of these and they seem to work fine on all the laptops I have access to.
However, the particular error you report ("no valid ROM images") is unusual and I'm not sure what to make of it. Are you running a particularly old kernel, by any chance? Like maybe 2.0.*? Can you use the card under Windows?