Yes, in a sense. It is actually more than just a USB to Parallel converter. It is a true motion controller which means it is specific to CNC interfacing. It also means that it "off-loads" much of the timing critical processing from the PC to this motion controller, freeing up CPU resources on the PC.
One thing of note: as you move into the newer Operating Systems such as WIN 8 or WIN 10, those operating systems put much more stringent limits to direct hardware access. Mach3/4 will not be able to communicate directly with the Parallel Port and will need to have a motion controller of some sort (with a compatible plug-in) anyway so this may be something you'll want to do to "future-proof" your system.
But the short answer is that most of the Motion Controller adapters should work with your laptop. I have the UC100 MC with plugs directly into the parallel port interface on my control box and connects to the PC through the USB port. Works great. Your mileage may vary with different MCs as the implementation is different from one manufacturer to another. It is dependent on both the hardware they provide as well as the plug-in itself.
Hope that helps,
Highspeed
EDIT: Here a link to the UC100: http://cncdrive.com/UC100.html You can also find them on Ebay, Amazon, etc. Or you can click on the "Distributors" button on that page and find one you prefer. I think I went with CNC4PC when I ordered mine.