Atomic Clock Sync
Full user review
"Simple, straight forward, does its job well"
Just as the title says: It doesn't try to do many things, only one thing, and it does the job right. Tiny footprint in memory means it uses practically no resources.
Can't think of any.
I downloaded this little clock synchronizer to replace a similar one that I had since Win98 but that had mysteriously quit working recently even though I've been running it in WinXP Pro for nine years. It turned out to be an updated version of the old program. I'm definitely satisfied.