Using CS5 is it possible to remove background noise. I have recently interviewed a person on a factory floor, and I find the background machinery noise is to loud. Is it possible to either remove this noise or at least make it quieter.

Various continuous noise removers exist as plug-ins, but random impulse noise like machinery is really impulse noise. The visual screens that exist in CS5 let you 'see' what you can hear, and this can help you see if the noise is isolated, spectrally from the voices you want to keep. The marquee tool can let you grab noise that is clearly separate. This, plus the usual eq available may help. Machine noise is often quite frequency specific. Perhaps if you let us have a sample, we could experiment?

Using CS5 is it possible to remove background noise. I have recently interviewed a person on a factory floor, and I find the background machinery noise is to loud. Is it possible to either remove this noise or at least make it quieter.

Probably not much you can do about it. It's sort of like asking how to remove the salt from the cake you just finished baking. The problem is that this noise occurs in the same frequencies as human voice.

If you get a chance to do this again in the future, consider that the only really successful way to maximize signal to noise ratio is to get the mic as close as possible to the signal source. For interviews of this type, I use a standard reporter's mic like the Electro-Voice RE50N-D/B. Works a treat, even on trade show floors, where the noise itself is human voices.

MAGIX Video Sound Cleaning Lab
Have not used it myself so not recommending, just informing
A decent audio editor such as Gold Wave will allow you to sample the portion of the audio track which only has that BG noise you wish to loose and remove those frequencies

Roy, is your "CS5" just PPro or one of the CS suites?

If you have Audition (or are willing to do a free trial of it or any of several competing audio applications), Process Noise Reduction should at least help. The greater the S/N ratio of your "signal" vs the "noise," the cleaner the end result. If you over-do it, quieter "signal" may become tinny, or under-water sounding so you'll have to tweak to taste.

Thanks to you guys for advice given. I think I'm trying to flog a dead horse. I've decided to do the interview again in a quiter spot. Then tape the sound of the factory seperate. Then put the two items on seperate tracks on the timeline and mix as required.