AFAIK any release of DKS more than 3 months old, or so, pre-dates either patch release, so if you didn't keep the patch (that you may have downloaded and installed last time you played), you'll most likely need it.
Run the autopatcher to check for updates (I don't have the PC version, but I'd guess it can be run manually). If you don't have an autopatcher, you need the
patch.
Another thing you could check is if you can start a new game in nightmare difficulty mode, which was added in the first patch.
