I was not able to select what contacts I wanted to have synchronized.
BS Editor: When I bought my Sony Ericsson K700i I realized that Sony Ericsson no longer include the XTND Connect sync software but instead their own PC Suite/Sync Station which is much more limited in terms of how you can select what you want to have synchronized to your mobile phone. I know that the same problem exists for P800/P900/P910 and many PDAs and other mobile phones.
My Contacts list in Outlook contain many hundred contacts, both business and private, many of which I havent used in years. So for me the biggest limitation was that I was not able to select what contacts I wanted to have synchronized. The solution to my problem was this piece of software I call the Contacts Synchronizer.
Even if Contacts Synchronizer is developed for use with a Sony Ericsson K700i it is generic and should work with any other mobile phones or PDAs such as Nokia, Siemens, Motorola, LG, Samsung.

How it works
Its easy as 1-2-3:
1. In Outlook you Categorize all contacts you would like to synchronize to your mobile phone, e.g. Mobile contact category. (In Outlook you add categories either in the bottom right corner of a contact card or Edit + Categories from the view)
2. Run the Contacts Synchronizer. It will copy all contacts that you have categorized to a new contacts folder, e.g. Mobile Contacts.
3. Run the sync software that was included with your mobile phone or PDA. In it select that you want to synchronize against the new folder that Contacts Synchronizer created (Mobile Contacts). you can free download Contacts Synchronizer 1.8.11.24 now.