I'm using XP and Vista and still have not been able to upload anything with Stanza. I can't get my Touch and Stanza desktop to communicate. It has been pretty good at converting books.
eReader is picky about the files I can upload to it's site so I haven't got that one up and running yet.
I haven't worked on either too hard because I can tell that the majority of my reading will be done on my Kindle. It's just so much more pleasant for me.
I am enjoying the iTouch immensely. It's rockin' my world. I had to laugh about it with a Mac friend of mine. He's died in the wool Mac and I'm died in the wool Windows. He recently purchased an Asus Eee and I bought the iPod Touch and we're both in love with our little machines. Something is wrong with the world.