Using a parallel-to-USB cable/converter is always a hit-or-miss, depending upon whether the drivers for the converter are available. But since you're using WIndows 7, i'm pretty sure it's not there. What you can do is to purchase an IEEE 1284 chipset/card which you will install on the Computer motherboard, and this will give you a parallel port, to which you can connect the parallel cable directly. I'm sure Windows 7 will have a pre-installed driver for such a card. Once this is done, connect the cable to the parallel port, and the printer should get detected correctly.
I am an ex-HP Employee. Currently inactive on the forum.