Remote patch installation?

With all the patchs and security updates that are coming out, I’m looking for a way to install accross the network. I have a small network of 200+ workstations, but I don’t have the time or money to setup sms so I’m looking for another solution. Ifanyone has a good third party software solution they would like to recommend or a home grown solution I could try, I’m more then interested. Thanks for any help you can offer.