Network Testing tools?

Does anyone know the name of the best network testing tools (preferably free
to inexpensive) that I can use locate bottlenecks in my networks T1 internet
connectivity and within my internal network?

Thanks in advance,

Mervin Williams

Ethereal (www.ethereal.com)

Matt Gibson - GSEC

"Mervin Williams" <(E-Mail Removed)> wrote in message
news:%23SzM5w$(E-Mail Removed)...
> Does anyone know the name of the best network testing tools (preferably
> free to inexpensive) that I can use locate bottlenecks in my networks T1
> internet connectivity and within my internal network?
>
> Thanks in advance,
>
> Mervin Williams
>