Hi,
Yes, if you download the package including MPLAB/MPASM then you might not get the latest but you should get one that should work.
You mention an older version being left on the laptop, is it possible that you've got MicroCodeStudio setup to point at that older version?

There's a tool called PBP_MPASM_Connector.exe (in PBP3\MPASM-MPLAB_Setup\). Run it and make sure that it points to the current version of your MPASM installation and not the old one.

I run PBP3 on two W7 64bit machines (and previously on one XP machine) and I haven't seen this /s parameter error - which again may have nothing to do with your initial question regarding the programmer.....

/Henrik.