How to keep MySQL general_log after I restart my computer?
Add this to my.ini

[mysqld]
log


If you have a specfic place for the log, such as C:\mysql_general.log

[mysqld]
log=C:/mysql_general.log
log="C:\mysql_general.log"


It's one of those. I haven't done mysql in Windows in a while.

Then restart mysql

net start mysql


Give it a Try !!!

CAVEAT

Prior to MySQL 5.6, you can use log.

In MySQL 5.6, log is deprecated. Use general-log instead.

UPDATE 2011-12-09 22:18 EDT

If you do not have my.ini defined, then you must define one.

To keep things simple, just create my.ini in the folder where my-huge.ini, my-large.ini, my-medium.ini, and my-small.ini appear. Just open up notepad on my.ini in that folder.

Then add the lines I mentioned before:

[mysqld]
log


or 

[mysqld]
log=C:/mysql_general.log
log="C:\mysql_general.log"


UPDATE 2011-12-09 22:26 EDT

In the worst case, try putting my.ini in C:\