When XP first came out, there were "many" reported problems on upgraded systems, but on new systems and clean installs these seemed to disappear. It was speculated that there Registry issues that simply weren't being handled properly in the upgrade process.
I've been running VFP 6 & 7 (~ 50% / 50%) on an clean install for 3 days short of a year, and haven't noticed any real problems. (Especially after installing the 4.83 Novell client.)
Note: I ran on NT 4.0 SP6a prior to this.
Rick