Virus protection is quite needless on Linux - unless you plan on running a mail server, from your netbook, and you want to scan all messages for any Windows boxes that use your server. However, I highly doubt this would be the case - therefore, anti-virus is something I needn't think you should concern yourself about.
Alternatives to iTunes - there really isn't one, that is, if you are looking for all-encompassing iPod support. Amarok, Rhythmbox and Banshee come close, though.
Word processors - take your pick. For small and fast, Abiword is really nice. For a complete office suite, though, try OpenOffice.org.