Thanks acid kewpie, I originally downloaded the 220.127.116.11 from the slackware cd 2 with the help of SlackDaemon. I guess the advantage of using that kernel was not having to answer a thousand and one questions that one doesn't really understand completely yet. When I downloaded the 2.6.21 I followed a link from linux archives http://www.kernel.org/pub/linux/
I then set about trying to find info on how to install it. Acid juices had straight forward installation info on the link below
I chose to download an already configured kernel via a link to Patricks config (config-2.6.10.)
which I of course updated to 2.6.21. Obviously there was something missing in that file that made it hard to install my cordless mouse. The keyboard works fine - it's just the mouse that is causing a problem. I am prepared to go through the process of configuring the kernel - just could need some more guidence. Have you a better suggestion regarding where to download my kernel. I try to keep to the stable ones. Once I get into the routine of doing the upgrade, patches and such like - I can go onto the more usual side of computers. I find linux fascinating -just need to learn a bit more.