The old 404

I’ve been running WP for a couple of months but we recently moved the whole site over to a new server, going from windows server to Linux. The whole of the site is working fine, we have a general front page a catalog powered by oscommerce and the WP blog. However since moving servers I can’t access the blog or the admin, just keep getting 404. I can see the files on the server and they appear to be in the right place, the file structure is the same as it was on the old server, but the pages are just not getting served. As I said, if I go into the hosting control panel, I can see all the files in my blog folder which is in the public HTML folder. Any clues anyone ?