PCAlive is an older program I need to do a rewrite of VERY badly – it’s built on .net 3.5 which means it has a stability problem – it gets a mysterious error message every once in a while if you don’t have .net 3.5. 
In any case though, the program’s simple – add the host/ip, port, and a name to display it as, push “Add 2 Active” and the program’ll let you know when it fails to connect to that system.
Here’s a small catch: the program doesn’t properly verify the server is actually -responding-. If it’s a webserver for instance, it might be able to connect but the webserver might have frozen or is under high load and can’t actually serve pages. If my rewrite goes according to plan (so don’t count on this ever happening) I’m going to try getting it set up so PCAlive can actually send a request to the system in question, and wait for a response.
For now though, here’s the link to the app. Tested on XP SP2 Pro but not on Vista cause I don’t have Vista.
Sysalive.zip [Download] OUTDATED; Look for SysAlive3’s latest releast in the Repository!
Source used to be available on request, but at the moment I’m keeping it close to the vest – it’s not anything Google couldn’t help you do over 