Removing BackGround Noise and Quality

(MacBookPro, Snow leopard)
I took my reel to reel tape (spoken voices) into a tape conversion service and had it transferred to a CD as a .WAV file.

The quality is very good, but there’s a lot of background noise, including a ticking cuckoo clock.

I know how to remove the background noise using Audacity effects, and to my untrained ear, it sounds better.

Question is: Does removing background noise affect anything else on the tape? Will I lose anything important? What should I look out for?

Thanks

If Noise Removal is used too aggressively it will damage the remaining audio, giving it a metallic bubbly sort of sound.