[IDEA] nTOP

[namtih]

I also installed additional small tools like nmon or atop and it's working fine.
As ntop also seems to be such small tool, just give it a try. If you're not happy with it, just remove it like "apt-get purge <name>".
I read that ntop has a small integrated webserver. So if you already have another webserver installed or if you use the webserver of XBMC, you have to change the port eventually to avoid conflicts.

And if you're still unsure, just create a full backup of your sd card before testing:
Win32 Disk Imager
http://sourceforge.net/projects/win32diskimager/