I wouldn't worry too much, the virus is quite old now but the problem is that some computers were infected and the owners are not aware of it. Originally the surrogate servers were going to be shut down in march, but they have been kept open until July to give people a chance to sort their systems.

If you have the virus then you obviously need to get rid of it as your computer will be slow and vulnerable.

The link you gave ( http://www.dns-ok.us/ ) is fine to use. But it only checks for this specific problem, you should always use a reputable anti-malware/anti-virus program.