Do you know how to get a pdf from pc to ipod touch?

When I downloaded some apps, it gave an error that means iOS3 on my ipod touch (3gs) is older and I ought to get newer iOS5. When I clicked yes to update and download, it first took me to download newer iTunes (10). I did so. Upon running the newer iTunes, it is asking to download another one, iOS5; and which is 600/700 mb. I ran out of my internet usage; and I cannot download so huge file now.

So after hearing to what I had been through, I ask you if anyone knows how should I go about to fix this problem? I need to copy some pdf ebooks (J.R.R. Tolkiens, for that matter) to my ipod touch. ipod touch runs iOS3. I cannot do it through wifi or internet; I have to transfer files from my pc (runs windows) to the ipod.

And, can I download iOS5 (or whatever newer most version) from my friends’ (that don’t have iTunes either), and install on mine?