I only have a few counties where the property cards have even been kept after theyve gone on computer and those are, for the most part, small, mostly rural counties.  Once the computers go in, they don't maintain the property cards, but I've never had a problem with them letting me access them if they still have them.  The only reason I resort to them, however, is assisting me in tracking the chain back.  If there's a break in the chain (due to a name change, death, etc.), sometimes they're my saving grace, but I don't rely on them except for something like that.