Does this mean we (and whoever created our HR software) have to sue IBM? Or can we just ask for a cut when they start collecting license fees on this patent?
No. It's a valid US patent.
It means that IBM can sue whoever created your HR software and get an injunction to stop its sale in the US. Whoever makes your HR software would then need to fight IBM and a team of wicked sharp lawyers in court, and convince a bunch of dumb-fucks in East Texas, who have nothing better to do for three months than sit in a jury for $12 / day, that the patent isn't valid do to prior art or obviousness.
Welcome to the giant cluster fuck that is the US patent system.