Extract a specific portion of a text string in Excel?

I'm positive this is possible to do, but I can't seem to figure out the right functions and order.

I want to extract a specific portion of a text, namely if I have the following in a cell as a result of using =CELL("filename",A1):

C:\Personal Files\[Filename Rev. CCC.xls]
or
C:\Personal Files\[Filename Rev. 23.xls]

I want to get a cell to have only the information between "Rev." and ".xls" (i.e. get CCC or 23 in the above examples). How would I accomplish this?

(As a side note, when I do =CELL("filename",A1) the filename has an extra space at the end. Any way to get rid of that?)