Microsoft Works is an "add on" program to Windows so may not be on your Vista computer.
Windows Vista has a built in calendar so you could use that, see here:
http://www.microsoft.com/windows/windows-vista /features/calendar.aspx
The usual way to get information out of a program like this is to "export" the info out of the one program and then "import" the details into the other.
Having said that, I am not sure if Works even has an export option on the calendar. And even if it has, it may be that Vista calendar cannot import a Works calendar.
So the first thing to find out is, when you are in the Works calendar, is there an Export option on one of the menus?
Try searching the Works help to see if there is anything about export in calendar.
Also, do you happen to know what version of Works you have on the XP machine?
Finally, do you have Works on the Vista machine or do you plan to use the bult in Vista calendar?