Some of y'all may recall I posted here months ago regarding the upcoming Windows XP SP2 and VFP. After extensive testing, we found only one small issue and that only pertained to 64-bit machines and an NX switch (dig around here - you'll see the post).
I've seen claims from customers on other forums that such-and-such stopped working after upgrading to SP2. This is unlikely. 99.9% chance we'd have seen it in our extensive testing.
Look at it from our perspective - if we'd found an SP2 bug that related solely to VFP, we'd be heroes! Brian Valentine would invite us to all his cool noshes where we could hob-nob with the Win team and utter "Yes, we reported bug number 2367253" while sipping white wine with an arched eyebrow. That would be so cool. If only!
So just do the upgrade and don't worry about your VFP apps. They'll work fine.