Usb - Ethernet adaptor driver query

Hi, I was wondering if anyone could help me with a problem. (XP OS etc)

I am purchasing an ethernet to usb adaptor as the ethernet port on my laptop has broken and i have no other ports on this laptop in which i can get an ethernet into it so that i can connect to the internet.

just this one
http://www.maplin.co.uk/Search.asp [...] checkstore

havent purchased it yet, but will do so in the next few hours, however the drivers for it are only a .sys and .cat and .inf, how do a get the device to work using this as there is no run install or whatever.

I found something on another website and this was the protocol that it said
"Step-by-step guide for install Infineon ADM851X USB To Fast LAN Adapter driver.
1. Download file for Infineon ADM851X USB To Fast LAN Adapter from our site, save it on your computer and unzip.
2. Connect your Infineon ADM851X USB To Fast LAN Adapter to computer.
3. Right click on My computer and click Properties. Go to Hardware tab. Click to Device Manager button.
4. Find your new Infineon ADM851X USB To Fast LAN Adapter on net category double click on device and press Reinstall Driver button.
5. Select Install from specific location, check Include this location and click Browse button to select the Infineon Technologies AGdriver click Next button to continue and click Finish button to finish installation.
6. After this procedure you should see new Infineon ADM851X USB To Fast LAN Adapter in net inside device manager."

This protocol was or slightly different drivers but are still a .sys a .cat and a .inf

Is this the way to go as the drivers i downloaded were straight off the website where I am going to buy the item.

Thanks for your time.