you don't have wifi on the compaq so you need a usb wifi adapter?
most adapters will work in one way or another, by using a newer kernel(we have that on pclinux, verify which one you have by opening console and write uname-r) or by using a windows driver and ndiswrapper present on the installation
i found this page but is in spanish
http://www.smc.com/index.cfm?event=viewProduct&localeCode=ES_CRI&cid=5&scid=31&pid=1545that could indicate that the model you are seeing is very old, it is just G so it only gives you 54 mbps, the company currently offers this one
http://na.smc.com/products/residential/wireless/smcwusb-n4/the one you ask, it looks like a generic sis wifi adapter, on the site you can find the drivers, it looks like it could work one way or another