The real question is whether or not you may need something that is on your computer while you're away. If there's a chance that you may need or want to access any files or data on your home computer then it would be a good idea to leave it on. However, if you want to have the ability to access your home computer from a remote location there are several considerations;
- Security: ensure that you are using a reliable firewall and that your system is up-to-date with the latest patches and updates.
- Means: there are several applications that allow you to gain remote access to a computer. "Remote Desktop" is a free application built into Win XP Pro but requires you to configure your firewall to allow the RDP protocol to pass through and also requires a client application to connect. Another great choice I would recommend is LogMeIn.com They offer a free application you can download and install to your home computer before you
leave on vacation and then while away you can login to the LogMeIn.com website, select your computer and access it over the Internet from anywhere as if you were sitting in front of it. LogMeIn is completely free, secure and works great. You can also check out GoToMyPc.com, they offer the same functionality but you have to pay for the service. The nice thing about a web-based remote desktop tool is you don't need to configure your firewall at all and no client application is needed to connect. All you need is an Internet connection to the web and your in.
The bottom line is though, if you don't really need access to your home computer while your away... Turn it OFF.