The two alternative books are:
1) "Developing Microsoft Visio Solutions" published by Microsoft Press in
2001 and which is now available on the MSDN web site. This book doesn't
include anything on vb.net and it's written for Visio 2002. For some reason
Microsoft didn't get around to updating this book for Visio 2003 which is a
shame because a lot changed for developers between Visio 2002 and 2003.
2) "Visio 2003 Developers Survival Pack" by Graham Wideman. This is an
excellent book which includes some C# but unfortunately no vb.net.
However, both books are useful as the VBA and VB6 code is relatively easy to
convert into vb.net. Another useful resource is, of course, the Visio 2003
SDK, which is available to download from
www.microsoft.com and which contains
some sample vb.net, vb6 and C# code.
Best regards
Roger Billsdon