Actually it'd be a very bad idea to learn vb6 then switch to .NET, because there lots of differences between those 2 versions. Huge Differences.
Professional Programmers who used to work with VB6 had difficulties switching to .NET, "There are more books on switching from VB6 to .NET than starting with .NET because it's much more difficult to switch.
so you can start with VB2005... it's easier by all means