Depends on what you want to do. .NET adds an additional layer (Foundation) to the system (as if anyone thought another could be added) which provides massive benefits as well as drawbacks.
Benefits: Better integration with new technologies. If you have a visual app (ie: video) you can take advantage of the new WMP/DirectX system. Object oriented language - If you can pick up C#, or even VB.NET, you've increased your marketing abilities to future employers... Speech, sockets, graphics, webservices, networking, etc, etc, etc...
Downfalls: Needs more horsepower. No doubt about it. Remember when VB6 came out? Really slow, right? Same story here. Your low-end PII won't run it (IMO). I'm uncertain about talking to Winamp. The standard Windows Messages may work, but I haven't tested them fully. What sort of overhead does .NET add in this area? It may make the whole thing unusable - VB is slow enough as is!
I'm currently contemplating re-writing my Carputer software in .NET strictly to take advantage of the SPEECH technologies. Main problem - Micro$oft is doing what they've done all along - Upgrading .NET on a YEARLY basis and not offering upgrades (or very short-lived offers and not advertising). So, I have to go blow another $100 on a new copy to get up to the 1.1 spec. Nice.
I'd advise against upgrading "just to take advantage of new features of the language". You'll constantly be upgrading. MS has new versions planned each year for the next 3, I believe. On that note - 2.0 this spring is supposed to be an unbelievable upgrade to 1.1! (Sorry about the rant - I'm a little sore on this point)