If your daughter needs to create documents/spreadsheets/presentations then an iPad (lacking a keyboard) may not be an optimal choice. I suspect you can't run MS Office on one (as it would contravene Apple's app store constraints) although you should be able to view most documents on it.
A netbook may also be unable to run MS Office - some will, some wont. If you need a netbook form factor then do some research before buying one.
If you have laptops already then you could just buy and install MS Office for one of them - the school should be able to provide a hefty educational discount.
If you're buying new, then consider the broader use of the laptop/netbook/tablet and buy something able to run MS Office as well as meet other needs (music/video playing, 'net access, etc).
Regarding the trojans/virii it's difficult to comment remotely over the internet. Start with a known clean system, with proper protection installed, use Chrome or Firefox with Adblock installed and assure that everyone using the system is educated not to download/run/click on/open/attach anything to it. That's very difficult in a family household
Bookmarks