VB and VB.Net are very similar. The difference comes not from OOP (object Oriented Programming) which VB6 does also, but from the use of global similarities within the .NET languages. Some features that VB6 has, VB .Net does not implement in the same way, although you can do some things exactly the same, the language was modified enough to make VB6 code have to be changed to run under VB .NET.
FTP/Chat: Of course you can. VB .Net still employs ActiveX objects, so you can still use WinSock and Inet Controls.
VB6, VC++6, VB.Net, C#, VC++.Net, .Net Assembler, as well as Borland C++ and Borland C++ Builder can all be used to create Voice Chat as well as Voice Recognition and Text To Speech applications through the use of SAPI (or Speech Application Programming Interface) which is on Windows 2k and XP (and installable add on to 9x/ME)
Hope this helps,
Chi Happens