Is there any way to get a macro to execute on a workbook
which is open, but not active?

I have a macro in a certain workbook (call it "A")which
repeats automatically but if I I open another workbook,
say "B", then the macro produces an error because it
doesn't find the data it needs in the active worksheet if
I'm working in "B".

I've added the following code to the start of my macro

Workbooks("hilowwork book.xls").Activate
Worksheets("UpdateInfo").Activate

and the macro runs fine but it causes the sheet to become
active and it interrupts the work I may be doing in
workbook "B".

Is there some way I can feed the macro the information of
the workbook name and sheet name that it is to operate on
so that it does this in the background and still allows
me to continue working in workbook "B" without
interruption?