iTunes adds at least 5 new processes... let's look at mine here:
issch.exe
iTunesHelper.exe
iPodService.exe
mDNSResponder.exe
AppleMobileDeviceService.exe
These five weren't present before my wife installed iTunes.
I've heard iTunes is a pain to get completely off of a system, but the GOOD news is that it seems that manually closing these processes seems to do well enough, at least on my system.
Eventually I'm going to get around to making another hardware profile, and disabling all of these extra things in that... but I keep putting it off...
Another option is to use a different software... I set up a program called "floola" on a friend's computer, as he was running Win2K and the older version of iTunes that was required because of the older OS wasn't compatible with his new Nano... worked like a charm.
Media Monkey looks good too, but doesn't convert unless you pay for it...