Macro that prompts user to select a file to open and perform another macro on this file

Greetings

I have spent the last couple of days trawling various forums to try and find a solution to my "problem." Basically I have macro (from here onwards will be referred to as Macro 1) which takes a set of data, formats it and then performs a couple of calculations. Macro 1 runs fine and always gives the correct values, however Macro 2 is what has me stumped.

I want to run Macro 2 in a "summary workbook" so that the user is prompted to select a file which is then opened and then Macro 1 is automatically performed on the selected workbook. Once the values have been calculated these values will then be copied and pasted back into the summary workbook. To summarise:

1. Run Macro 2 in "Summary workbook"
2. User is prompted to select another workbook
3. "other workbook" is then opened and Macro 1 is performed on it.
4. Once the values in "other workbook" are calculated these are then copied and pasted into the appropriate cells in "Summary workbook". The two cells that will be populated in the "Summary workbook" are next to each other in the same row so I am guessing a simple copy and paste would work but the appropriate cell would have to be selected prior to running macro 2.

May be asking a lot here, but would like to know if it is at least possible before I expend any further time/energy on this "project"

Thanks in advance

Matt