After some experimenting I ended up with the following
which works great. I had to add the ping line to add a delay so that
Excel 2003 has time to open  before the command to open the target file
is executed:

start "C:\Program Files\Microsoft Office\Office12" excel.exe
ping -n 5 127.0.0.1>nul
start /d "C:\Documents and Settings\Pete\My Documents\PD-
Trak\Development\6.2.2" Open_PD-Trak.xls

I also had to add an underscore in place of the blank in the file
name. I tried using %20 instead but without success. A minor
compromise. Thanks again!