How often to reboot.

Hi techies,
I’m running a NT 4 BDC which also acts a file and SQL server for my network.
For the 2nd time in 3 months the server ran out of allocated memory and had to be rebooted.
I suspect 1 or more of the programs has a slow memory leak but asthere is no way to check this I’d like to reboot the server ever so often.

My question is: How often should I reboot the machine to avoid this from happening ?