Sorting Groups of Data in Excel 2003

I apologize in advance if this is hard to understand. I am a newbie and pretty much teach myself, but I can not figure this out!

Is there any way to sort a column of data that is designated to a specific group? I have attached a sample to easier explain what I am trying to do.

In the attachment, there are three groups of data. I need to sort each group by column G (from lowest to highest). Obviously, the stickler here is keeping all the rows within the groups intact. I have a huge spreadsheet of this and I am really dreading the idea of having to do this manually!

Any solutions? Thank you so much in advance.

I am using Excel 2003, but I could possibly use Excel 2010, if their is an option there.

Sample.xls