Thank you, all, for the suggestions. As it stands, we will install one computer per library and if BSNL get their act together, each one will have an Internet connection. However, the latter is not a given.
Amongst the suggestions, a common thread, barring Eugen, is ways and methods to 'secure' XP. Surely Ubuntu would be a better bet? I was rather hoping for arguments that I could use in favour of that. But, I suppose, freedom of choice would mean giving the end user the ability to use XP or Ubuntu. Though I'm not sure we have the resources to maintain both. Cheers! -Gautam