App Compactor on regular programs

Has anyone tried using App Compactor on regular programs i.e. MS Office, Internet Explorer? I'm working for a non-profit and one of their computers has only an 8GB hard drive. I've done everything I can think of to open up some free space, and since the organization feels that the particular machine is not worth shelling out for a new hard drive I'm doing all I can under the circumstances to help it run faster. I'd like to try compacting the above mentioned programs to squeeze out a bit more, but first I thought I'd ask if there would be any problems with doing this. I've used it on some apps like winamp and other non portableapps.com USB releases to great results but I'm just a bit nervous about trying it without some better info.
Thanks,
Edmenje