I don't want to use a *nix file system because XP won't read it nativly. That leaves Fat32 which both can read and write. But doesn't Fat32 limit file sizes? I would like to use this as my home ...

How to Open DOCX Files on XP. If your business computers run XP and you don't use Microsoft Word to manage documents, you may find the Microsoft Word Viewer useful.

At least, to my I've-not-used-an-iPad-really-before mind this is the only other route I've figured for this rather inclusive file management system. Have you managed to make iCloud work on Windows XP?