I had foolish idea this friday afternoon. I was at the office and i tested an upgrade from CentOS 4.4 i386 (32 bits) running on a IBM HS20 Blade server to CentOS 5.0 X86_64 ! Some will say (and i agree) that such thing is a silly thing to do , but the sun was shining and i had to reinstall the blade anyway ... But strangely, it worked ! I upgraded with Anaconda (through an NFS install). The only problem i had was related to udev and linuxwacom. I had to remove the old udev package (that was left behind) and verify the newer one ... but after that everything was running perfectly ! Of course that's something i'll never do on production servers ... :o)