I recently upgraded to KDE3.2.1 and the 2.4.25 kernel. I had no problems with xfree86.
Two gotchas occurred elsewhere though.
1. My /etc/resolv.conf was replaced with a new file (the old one was saved with a new name, I think! unless I kept a copy when I set this up. I don't remember). This caused a problem with my internet connection as I lost the DNS addresses stored here.
2. I installed the updated CUPS package, which clobbered my LPRng printing setup. I just reinstalled LPRng and all works fine again now.