I was just about to write that you can find the version by opening the error log file on the old machine.
The last thing mysql writes when it starts is something like this.
140328 9:16:20 [Note] /opt/mysql/mysql/bin/mysqld: ready for connections.
Version: '5.5.18-log' socket: '/tmp/mysql.sock' port: 3306 MySQL Community Server (GPL)
My machinne is running V5.5.18.
anyway, V5.0.51a would be the same for Windows.
You can get it from the MySQL archives.
http://downloads.mysql.com/archives/community/
Select V5.0.51a from the select list.
If you know the root password for your old installation on Debian, then you can include the /data/mysql folder in your copy if you use the same version of MySQL, because all your usernames and passwords are stored in there, along with a lot of other stuff.
After all this is done, can I suggest that you make regular backups of your database? Restoring from a backup is SO much easier.
Good luck,
Barry.