The 2005 beta is pretty awesome, and its free.
The easiest version just to start fooling around is VB 6.0, but you can't buy that anymore, as far as I know, and its use will be limited in the future. The current version of VB.Net is not bad, but the new 2005 version will be a huge improvement. I would download the free beta edition (it's solid) and then get a student or standard edition of the 2005 version when it comes out.
I started out in Visual Basic 3.0 and was hooked, and still program in VB 6. I haven't decided if I'll do any new development in VB.NET or C#, but C# seems like the better choice from a career standpoint.