Web Services, merging, datagrid

I want to run a query using a web service that pulls in datasets for the TOP 100 records at a time and populates a datagrid on the calling form. The user could hit the "Next 100" button and merge the next 100 qualifying records from the database. So, my SQL statement says something like SELECT TOP 100...etc. Hitting Next 100 performs a similar query but starting with the ID after the max ID from the last dataset. I tried to pull this value from the datagrid but couldn't seem to get to the value. For example, grab the ID that was in the last row of the datagrid. Unable to do this, I set out to pull the info from the dataset on the web service. I was able to get this value (and the rowcount, which I also couldn't get from the datagrid) but couldn't figure out how to pass it back to the calling form as my web service is a function defined as a dataset:

Public Function GetValues(ByVal strSring As String, ByVal Type As Char, ByVal X As Boolean, _
ByVal Y As Integer) As DataSet

I'm brand new to VB.NET and may be overlooking something painfully obvious. Anything that could point me in the right direction would be wonderful.