I'm trying to do up a line chart based on a table on 'Project Summary Report'
sheet. I recorded a macro and Excel generated a series of codes as follows:

Charts.Add
ActiveChart.ChartType = xlLineMarkers
ActiveChart.SetSourceData Source:=Sheets("Project Summary Report").Range( _
"A1:C4"), PlotBy:=xlColumns
ActiveChart.SeriesCollection(1).Delete
ActiveChart.SeriesCollection(1).XValues = _
"='Project Summary Report'!R2C1:R4C1"
ActiveChart.SeriesCollection(2).XValues = _
"='Project Summary Report'!R2C1:R4C1"
ActiveChart.Location Where:=xlLocationAsObject, Name:= _
"Project Summary Report"

The values on the active sheet are actually generated from a query in Access
2003 and are automated to be displayed on an Excel spreadsheet. In other
words, the query result set can get bigger.
An example: 1st row indicates the column names "A", "B", "C" while 1st
column indicates the rows "1", "2" and "3"
----A-------B--------C-----
1---Week--Target--Actual
2---1-------3---------3-----
3---2-------3---------4-----
4---3-------4---------5-----

My question is does the range that is generated from
ActiveChart.SetSourceData Source:=Sheets("Project Summary Report").Range( _
"A1:C4"), PlotBy:=xlColumns
vary accordingly?
Do I have to declare a variable say, 'rowCount' as
worksheet1.UsedRange.Row.Count so that a variable range can be defined?
Same applies for
ActiveChart.SeriesCollection(1).Delete
ActiveChart.SeriesCollection(1).XValues = _
"='Project Summary Report'!R2C1:R4C1"
ActiveChart.SeriesCollection(2).XValues = _
"='Project Summary Report'!R2C1:R4C1"
Do I have to declare a variable for the range of SeriesCollection(1).XValues?

Thanks in advance.