are you not using outlook? ( i dont have Vista)
added
try these
http://www.everythingicafe.com/forum/windows-pc-and-iphone/another-calendar-sync-solution-8308.html
http://www.vistaheads.com/forums/microsoft-public-windows-vista-general/197410-cant-sync-iphone-vista-home-premium-windows-calendar.html
Windows Vista does not use Outlook, they use Microsoft Mail. I've not gotten up to speed yet on my one computer that has Vista, but I can say that you don't want to sync the iPhone to more than one computer. It really gets things mixed up.
I have XP at work and we use Outlook for our company calendar. I sync the calendar there but do all my other sync's on my home computer. Music, ringtones, etc get all mixed up because you delete one to sync with the other.
I've had my 3G for about 3 months and like it very much, but have found that even with good signal I drop calls quite frequently. I was just in Michigan for Christmas and all I could get was the Edge signal and things do not work well on Edge. It takes forever to download e-mails etc.
I've found the
http://discussions.apple.com/category.jspa?categoryID=201 to be very helpful. Do a search for calendars or something like that and you'll get lots of hits.
I'm not even close to understanding all the unique traits that this thing has. I've downloaded free apps from the Apple App store and sometimes they just quit working and I have to reinstall them. So far I've not paid for any apps and only used the free ones. I use the Translator about every day at work. Units is a good one to figure out any conversion factor from inches to metric, or volume, time, space, continuum

, I had to do that...
So far though it's been a big help with my everyday issues. On our drive home from Michigan we used the dictionary for the wife on her word find book and we looked up some music we heard on the radio. There is a FREE app that is called Shazam and it listens to the song and then will tell you what it is and who is singing it. It has to go through the iTunes store though so 3G or WIFI is the only way to use it. It's great.
Go to the Apple Disscusion forum and you'll get taken care of very quickly.
Good luck.