Visual Studio.Net is based on the .NET platform.. which emplys the Common Language Runtime of Microsoft for helping to integrate codes written in various languages like VC++.net, Vb.net etc..on the other hand VB6 is not based on the CLR, meaning that u cant intergrate the code with any other language..(u dont need either..just my two pence)..
moreover, VB.net is FULLY object oriented..while it is not so well implemented in VB6.
in my opinion..VB.NET is very much a bloated and heavy language..easy to learn..but keeps u handicapped as a programmer...i think its best usefulness is limited only for developing web based applications(if someone here works on this..i'll welcome you to correct any mistake in this statement)..if u want to go into .net..try to learn VC++. it's a beast to tame..but it IS a beast.
if u r just developing a basic stand alone application..VB6 should be good enpough for you.