About the internet.... that is a tough one. Not sure if there were ethernet to local talk adapters (the IIsi has a special 9 pin thingy that was used for networking macs using the Apple talk protocol). I'm sure there are NuBus ethernet adapters, but from the sounds of things, your IIsi has a nubus video card plugged into the bridge card. Keep that for video. I remember when I put a 24 bit video card into mine.... it was like having a new machine.
There are a few ways to get the IIsi on the Internet. And other than an Ethernet card, none of them is particularly pretty. Obviously, there is dial-up, but that is an added expense for something that is realistically just a novelty.
The IIsi has 2 9-pin serial ports, respectively referred to as the Printer Port and Modem Port. For the most part these ports are interchangeable. Other than using a dial-up modem, there is another way to gain Internet access through these ports... but you need an AppleTalk / Mac IP router. To do this you either need another pre-USB Mac with an Ethernet port setup with AppleTalk IP software, or you need a device such as the Gatorbox ( http://en.wikipedia.org/wiki/GatorBox
), which is what I have.
Another way to get the IIsi on the Internet is with an ugly little abomination of a device called a SCSI-Ethernet adapter. Yuck. I also have one of these... the Asante EN-SC ( http://lowendmac.com...ra/05/1129.html
). I bought it before I got my Gatorbox, so I could get my Mac Plus on my cable modem. The nice thing about the Gatorbox is that you can daisy chain many computers!
IMO it's not worth the hassle, but that's for you to decide.
You would probably be further ahead buying an Apple CD-ROM drive and transferring any files from Windows like that.