I'm InTouch Premium
You download and configure I'm InTouch Premium on any PC that you'd like to access remotely. Configuring the app is a bit more convoluted than it should be (for example, you have to enter a nickname for your PC in two different places), but overall it doesn't take very long.
Once the software is running, you point your Java-enabled browser (from a wired computer or wireless PC or handheld) to locator.01com.com. Here, you'll see a list of your available PCs and their status. If your PC is online, you can view your desktop, or access your e-mail account, files, or any installed Webcams.
If your PC is offline, you're prompted to activate the Remote Wake-Up feature. While this is an extremely useful feature, it comes with some serious limitations--the first of which is that you'll need two PCs running I'm InTouch Premium on the same wired network to use it. So if one of your PCs is at home and you left that PC turned off, you're out of luck. A PC on that same network--one that is running I'm InTouch Premium and has been configured as a "Wake-up proxy"--will have to be turned on; it sends a signal to the other PC in order to turn it on. It also can take several minutes to turn on the PC, and you may have to fiddle with the (again, convoluted) application settings to make sure this feature is activated.
I'm InTouch Premium also includes administration and account management features for small and mid-sized businesses. With its premium price and the limitations on its Remote Wake-Up feature, this product will work best in an office setting, where you have multiple PCs connected to the same network.
Note: I'm InTouch Premium pricing starts at $12.95 per month for two PC licenses (2 licenses is the minimum purchase); each additional license (up to 10, total) is another $9.95 per month.