Please tell more about "installed". Did you install a Windows 7 compatible driver? Does it show in Device Manager without any errors and 'working correctly'?
Just today a friend brought me her old PC with a USB Wifi thing, that worked under her XP home. After setting up her new Windows 8.1 PC (and copying her files) I'm supposed to get that working. So I need to find a Windows 8.1 driver for a Sitecom WL-540 CA. And then I expect it to work.
The driver in your Windows 7 should fulfill all necessary functions that aren't included in a standard Windows installation, just like her driver does everything that's not included in her XP (and hopefully, in her new Windows 8.1).
I have an Acer as[pire 3400 desktop, operating windows 3 home. I was advised by acer that this model did not operate with wif fi. Because of distance problems I deided to see if I could install a wifif system in my home and was advised that this model Pc would require a USB adapter, I duly aquired a TP Link apapter model TL WN822N. This was installed and the modem connected to the phone input. Ther adapter did not recognise any signals. After valianty efforts the adapter was taken away and set up on a firiends PC where it worked perfectly. The modem also indictaes that it is producing wif fi (my wifes kindler roks fine) A engineer looked into this and advised me that the softare on windows 7 associated with wI fi is either missing or corrupted. I approached Acer who kept repeating that this model PC was not built to accept wifi - of which I was aware which is why I obtained an adapter! Suggestions have been that I should perform a system recovery back to factory default. However I am advised against this (drivers back ups etc?) is there anyway I can check that the pre installed windows (oem) 7 can be set up to operate with wi fi or am I chasing a dead horse?? Acer just keep telling me that "this model does not operate wif fi" Any and all advice welcome, for which many thanks Dave