Technically, the "first" Corpse Party that's being brought to PC is different than the one you can get on sale as part of this deal. The PSP version was effectively a remake of the PC version that's on its way (which was, in itself, a remake of a 1996 PC game) and boasts a fair amount of unique content.
Incidentally, I cannot say enough good things about this series. If you're a fan of 999, Virtue's Last Reward, Danganronpa or other visual novel titles, you owe it to yourself to pick up these now super-affordable titles, put on some earbuds / headphones and settle in for a memorable horror experience like no other.