In general:
http://www.cablesdirect.co.nz/www/pdfs/laneu4203.pdf
[warning: pdf]
The Hi-Speed USB 2.0 to Fast Ethernet Adapter allows you to connect to the network at 100 Mbps Fast Ethernet throughput speeds. But not all adaptors are made equal and we don't know which one you are talking about.
In linux, all
full speed 100baseT usb/ethernet adapters
are reported as working, as well as high speed 10/100 adapters.