I have just recently purchased a notebook that has vista on it. I have found that midi yoke does not work on it but midi maple does work on vista. I have also found that if you have a notebook with an integrated audio card that is inadequate for your needs, Creative and e-mu are now producing cards called (express cards) PMCIA if you have that port. This can be used instead of the integrated card. Just fyi for anyone using a notebook.  Creative has a card called x-fi that has just come out and will be available in about a month and e-mu has very expensive express cards $350-$450 available currently. The current cheap model is made by Creative and is a Sound Blaster Audigy card that you can get from dealers such as newegg and tigerdirect. These are sold for about $75 and will work for the time being for most needs on your notebook.  Also has anyone else had trouble loading vdl2 on a vista os machine? I can load almost every sound but some of the mallet sounds. I do not get this problem on my desktop xp service pack 2. Let me know if you have any ideas in regards to vista os.

Native Instruments has not yet announced official support for Vista. There should be some sort of official word on this development in the future, but for now XP is as high as they're officially supporting. That said, I've heard that there aren't major functionality problems, but there are simply some things that need to be worked out in terms of passing certificate and uninstaller updating.

I don't understand why most sounds would work, but not mallet sounds. Knowing how the Kontakt Player locates encoded samples, there's no reason those shouldn't load if your other instruments are loading. Not sure if I can give you much help there, but you might try submitting a support request with NI at:
http://www.nativeinstruments.de/index.php?id=suppform_us

Since you're attempting this on unsupported Vista, you might not get much love, but it's worth a shot.

Thanks for all the soundcard suggestions. I'm sure that will come in handy for many users!

I've run Kontakt 2 in Vista without any problems.

However, I have not personally had good experiences with PCMCIA sound cards.  I own the Creative Audigy 2ZS and it is unreliable at best.  It is very picky about how it's installed and the sound isn't all that great.  If you don't mind carrying around a little extra bulk I recommend getting a USB or Firewire interface.  I have the Fast Track Pro by M-Audio ($200) and have been EXTREMELY satisfied with it.  It's way better than the Audigy 2ZS, both in terms of ease of use and sound quality.  Plus, it has mic pres with phantom power for recording.  The only major problem is that as of right now they don't have a Vista driver for it.  However, there are tons of USB and Firewire solutions out there.

Edirol UA-101 -- USB, and has a working Vista 64-bit driver.