I have not tried Windows 7, but its disk manager is probably the same or better than in Vista. I have used the Vista disk manager to delete and enlarge partitions successfully, although not often enough to describe the process.
If your Windows 7 installation is functional try its disk manager. The one in XP is not as good. You might not be able to do everything in one session. I sort of remember having to restart the computer after deleting partitions before I could enlarge the adjacent one, but try it and see. It might work better than a free 3rd-party app.
To open Disk Manager, click the ‘Start’ button, right-click ‘Computer’, select ‘Manage’.
In the ‘Computer Management’ window, select ‘Disk Management’ from the tree on the left.