I realise there is some other questions and info about replication and syncing but had hoped to get a fresh answer based on my requirements.
Main database is SQL Server 2000 Standard and has a few tables with 100k rows with inserts / updates every minute or so. Target databases are SQL 2008 Express over VPN and each site would require its own subset of the data, a synced view would be preferable but would be happy to sync all 6 tables required as long as it is only the filtered data synced. Sync would be hourly at most with option for a forced sync.
What would be the best option out of all the replication options, DTS, sync services, linked servers with SQL Agent jobs or .net service for this task?
Just a note on the database size on SQL2008 express which is limited, in your case replication suits well as you need subset of data. You must look at the data which needs to be transfered between the instances, see this http://www.sql-server-performance.com/articles/dba/replication_across_internet_p1.aspx article fro more information.