Hey, Katy:
You are completely making sense. Do your technology systems have unique Ids? You could add a node to your form's main data source called something like "SelectedTechnologySystem" or some such, then, give the user a button next to each row (you can make it look pretty slick if you dump the borders and shading and use a cool character from WingDings or one of those special character fonts). The rules on the button with set the value of your SelectedTechnologySystem field and switch to the email view. THEN, in your email view, where your repeating table or section bound to the data source with the Technology Systems is, you can add conditional formatting to only show the item that has an ID that matches the value in SelectedTechnologySystem.
Does that make sense? Actually -- I'm just attaching a sample form, that will help more. Right click the link in the header to my post, save the file locally, and then right click the saved file and select Design to open in design mode. You can then preview to see what I mean....