I have found three kind of connections when installing a NIR to a Computer: Serial Port, USB and RJ45.
Now is quite difficult to find a computer with a serial port, so the best option is to connect an adapter from USB to Serial RS232, but I have found that some of them performs fine to all the instruments and software´s, and others give connection problems. The adapters come with the drivers disk
USB connections are not a problem, because all the computers have several USB ports.
Some new NIR use the Ethernet connection RJ45, and normally all the computers have one, but we need another to connect the computer to a Network and Internet. We can buy a RJ45 board and install it into the computer, but I heard that in some cases is not easy the configuration, so one easy and quick solution is to connect an adapter from USB to RJ45. There are several in the market. They come with the drivers for 32 or 64 bytes.