First off, I'm really, really new at doing things in Excel.

Second off, I only have Excel 2003.

Okay, so.... I have two workbooks. One workbook (A) is pulling a sum of
about 20 or so cells from another workbook (B).

I want to be able to update Workbook A with the current values from Workbook
B without having to close and reopen it (I update workbook B every half
hour). Is there a process or macro, or something I could use for this?
Workbook B also stays open and has to be opened in a separate Excel program
(It has an update feature itself that messes up if I have another workbook
open in the same Excel program.)