Thanks for responding.
I have XP Pro SP3
I re-installed the drivers from Sony, ostensibly 10.5.1.59.
My wireless is working fine, but I'm getting an error message telling me that my driver 12.20.11 is incompatible with my software 10.5.0.1 and sure enough, when I look at what is installed, it's 10.5.0.1.
Intel is up to version 13 or so and doesn't appear to support earlier versions.
Maybe I should strip everything out and do a complete re-install. Does that make sense?