My iPhone 4 syncs to MacBook, but MacBook contacts, calendar, don't sync to phone

This just started - used to work fine. Not sure if it was an update (I'm using OS X 10.5.8), or it may have coincided with starting to use iCloud. Gotta have my dates and contacts on my cell! Help!!

Yeah, it's to do with your Mac not being on iCloud.

Problem is: if you're using 10.5.8 in this day and age you must not have an Intel Mac. Which means you can't update the Mac for iCloud (10.7.x only).

If you DO have an Intel Core2Duo Mac, then you're overdue to upgrade to put it mildly. You'll need to buy Snow Leopard, install it, update it, then use the Mac App Store to buy Lion, install it, update it and turn on iCloud.

As that may mean a lot of application updates, think carefully and plan ahead if you pursue this route so you don't fall into any issues.