If you are determined to implement Gnutella in VB, then I won't stop you.
But remember that Gnutella is no longer as "simple" as it was in the 0.4 times.
Please have a look at
Gnutella for Users - Gnufu to get a glimpse of the concepts you'll have to implement to create a compliant Gnutella client.
(I'm working on getting the specs wiki up again at the moment).