"Is Visual Studio still worth getting? Which version to go for?"
Yes! If nothing else, get the 2010 Express edition
] in the language of your choice (VB, C# or C++) - it's free, and very, very good.
DCOM is not something that would be designed into a .NET app at all - Sockets or WCF have pretty much rplaced it.
.NET is pretty good - it is consistent (unlike MFC) and covers most of the hassle stuff - you just get on with your software instead of faffing with the lower level stuff. It isn't that big as far as users are concerned - Windows 7 includes .NET 3.5, and Vista included .NET 2.0, so it's only if you are developing for XP or .NET 4.0 that it needs to be installed at all. Remember, it is effectively a complete operating system over the top of Windows, so it is going to be a bit bulky. Is it worth learning? Do S/A apps exist any more? Yes, and Yes - it's horses for courses, but the very consistency makes it a bit easier to pick up.