there are two easy ways that I know of to fix this.
1. Run it with Koala Player
http://www.koala.pl/Index2.php?page=Index&lang=en
There you can very easily adjust the timecodes for the subtitles foreward or backwards. When you do it this way you can adjust it just little by little and try it out to see if it's right. Then just save it when done.
Be sure to get the 2.5 version though, as there is no working crack for the 2.6 XP version (that I have found atleast)
2. Do a search on your computer for a file called 'subresync.exe'. If you got VobSub installed (most people do) it will be in that directory. It should be fairly easy to adjust it there too, although I haven't tried it myself.