With the "if it ain't broke, don't fix it" philosophy in play here, I would check out this article on Computerworld magazine's web site:
How to make Windows XP last for the next seven years
"If you've got Windows XP, worry not -- you can keep it running on your hardware for years to come. As with an old car, though, if you plan to keep XP around for a while, you're going to have to spend some time maintaining it. Think of us as your virtual mechanics. We'll give you tips, tweaks and tricks so that you'll be able to keep XP running smoothly, at top performance, for smooth operation and long life."This article will help a cash-strapped congregation keep using older-but-functional hardware for several more years.
"The company's standard life-cycle policy provides bug fixes and security patches (known as mainstream support) for five years after initial release, and security-patch-only support (known as extended support) for an additional five years. Although Microsoft often doesn't provide extended support for its consumer products, the company says that XP Home and XP Pro will get identical support periods."
"Microsoft's support road map currently says that extended support for Windows XP ends in April 2014. You need to be on the latest service pack within one year of its release for continued support, which at this point means you must be running XP Service Pack 2."