How to use myisamchk?

I’m using WP locally (on Windows), powered by a bundle of Apache 1.3.27, PHP 4.2.3 and MySQL 4.0.0. After running Mark’s better search script, I started getting errors when trying to access my site (errno 145). The wp_posts table crashes everytime I try to edit a post, and the REPAIR TABLE command only solves the problem temporarily (until the next editing attempt).

I understand that my db was probably corrupted before trying out the improved search, just wanted to provide context. Mark suggested running an ISAMchk, but I can’t seem to figure out to do this: myisamchk -r -u root -p databasename. Or how to handle shell/telnet/ssh. Could someone offer a step-by-step guide from the moment I click Start -> Run?

Thanks really a lot.