I have a Mac Mini that I would like to login remotely from a Windows XP laptop. Is this possible? What types of things do I need to do to allow remote connections from the Mac, and what type of interface will I be able to have? (Command-line interface? Or full GUI interface?)
SSH is installed by default on OS X. You just need to download PuTTY on your Windows machine and connect to your IP. SSH provides console access.
If you want a GUI you can use VNC.
You can enable the ssh daemon on your mac by going to
System Preferences.app -> Sharing -> (enable) Remote Login
You can enable screen sharing similarly with
System Preferences.app -> Shareing -> (enable) Screen Sharing.
If you are not using the Apple Remote Desktop software, you'll need to do the extra step of clicking on the Computer Settings button, and supplying a VNC password
This isn't the free option, but if you have two macs running Leopard and a MobileMe account you can use Back To My Mac to connect to the other mac's desktop. Here is a quick screencast of this feature.
I use these this web site. You need to sign up but you can access you choosen computer. I use to to fix my dad's computer. I use the basic free versio. Works fine with both Mac and PC https://secure.logmein.com/