Locating GPIB-USB-HS Driver

Hello ,
I have a measurement interface that had been developed on labwindows and it had created a distributor. I have the interface but I'm not the source code.
Before that he communicated via GPIB -GPIB.
But I have a PC that I want to communicate GIPB/USB with my spectrum analyzer.
Think about it with the GPIB/USB  of national instrument it will work thank very much