How do I sort events created by different clients based on a global clock?

I have a newsfeed program, and I've got many client applications (about 70) across a f开发者_如何学Goew timezones that generate events, for example when a secretary schedules a meeting it adds to the list on the server. This list is served to every client that wants to view it. Currently each record has the following metadata:

• random unique ID
• local timestamp (YYYY:MM:DD:H:M:S:ms)

How do I sort these events on the server, such that they appear in the correct order they were submitted in? Currently they get mixed up since local timing doesn't match. I don't have any UTC timestamps (can I calculate these locally?), so I'm wondering if I can make-do with the information I got... or should I be getting more information from each client? I noticed even clients in the same timezone get events mixed up because their system time is not synchronized (is it possible to know the exact global time, or synchronize the system time with a server on Windows?)

I'm not asking for code, I just need a pointer in the right direction.

When storing temporal values it is essential to always use UTC. Anything else and you're screwed. You really should also store the related timezone along with the UTC.