I recently moved my VDL 2.5 to new computer.  I reinstalled the program and downloaded the pact installers that work with the new MAC OS Leopard.  I followed all the tutorial instructions in installing both VDL 5.2 and 5.2.5 .xml sound set files.  I then loaded my Sibelius 5 and I cannot get the playback devices to show the sound sets that I installed.  So far I cannot load the Kontakt Player also when I tried to load the stock VDL 2.5 I get a prompt from Sibelius saying that Kontackt library is not installed properly.  I followed the instructions on Bryan Harmsen commenting on Kontackt Player Library Problem and I still have been unsuccessful in getting Sibelius to offer the sound sets as an option in the Playback devices window of Sibelius.  Sibelius is working correctly other than that.

Any Help would be appreciated!!!

If I'm reading you're post correctly, you're experiencing two problems:
Problem #1 = No VDL Soundset available within Playback Devices
Problem #2 = KP2 is telling you the VDL library is improperly installed.

Let's take a look at these one at a time:

[b]Problem 1:
[/b]
Double-check to make sure you've correctly installed the sound sets (these are the xml files that come with the various Sibelius templates). On a Mac, there's two possible locations these could be residing. Check both of these locations, and make sure the XML files are living in ONE of them:

Macintosh HD>Library>Application Support>Sibelius Software>Sibelius 5>Sounds

OR

Macintosh HD>Users>[i]yourusername[/i]>Library>Application Support>Sibelius Software>Sibelius 5>Sounds

Now...
TRIPLE-check to make sure the xml files live in one of the above locations. Once you've done that, carefully check again.  :)

[b]Problem 2:[/b]

Launch KP2 in STANDALONE mode. Once it's open, in the LH library column, do you see the stainless steel background for the Virtual Drumline library, or is is kind of an ugly, plain blue? If it's the latter, somehow KP2 is looking in the wrong location for your library files.

1) Verify the location of your VDL 2.5 .nkx files. Usually, these live here:
Macintosh HD>Applications>Tapspace>Virtual Drumline 2.5

If you don't see them there, one of two things may have happened:
A - When you drug those NKX files from the DVD onto your hard drive (after running the Leopard installer), you put them somewhere else.

B - You may not have drug the previously mentioned NKX files into your library folder. For a refresher, the simple instructions are listed [url=https://www.tapspace.com/Downloads-Updates-p-2.html#VDL25LeopardInstaller]here[/url].

2) Once you're certain that your library is all contained in one location (this includes the ";instruments"; and ";multis"; folders as well as the NKX files (should be 4 of them: .001, .002, .003, and .info), click the INFO button on the VDL area of KP2. Then click the button to CHOOSE your ";library installation path"; and make sure you navigate to the [i]exact[/i] folder where you're VDL 2.5 library resides.

3) Once you've done that, quit KP2, then re-launch it. If you've successfully re-navigated to the correct library path as outlined above, you should now see the stainless steel background for the VDL library in the LH column.

One other recommendation I would make (if you haven't already done this) is to download the VDL 2.5.1 updater from the NI Service Center program. This will update your Kontakt Player and VDL library. There's also an outside chance that if your score contains instruments from the VDL 2.5.1 library (such as 4-octave vibes), but you haven't yet updated your VDL to 2.5.1, it'll give you the message that the library isn't properly installed.

Take your time to carefully read through the above advice. These are fairly common problems that are usually the result of user interjection. Please let us know how you get on.

OK 
Problem #1
I really feel like an idiot I triple checked that I correctly installed the xml files in the correct location.

Initially I had put into

Macintosh HD>Users>myusername>Library>Application Support>Sibelius 5>Sounds

I then tried to move it to

Macintosh HD>>Library>Application Support>Sibelius 5>Sounds

However this folder did not contain the same files the other one had (it was empty is that normal?)

I opened Sib 5  after every attempt tried to load the KP2 instances and I still could not find the sound sets.  I even clicked on the Audio Engines Option Button to rescan for virtual instruments and restarted Sib 5 every time.  I still could not get the sound sets to be offered.

Could it be a problem with the xml files themselves? 

I write on two computers and these files work on my other Imac (OS Tiger) fine.  Could it also be a problem with my Sibelius?

As far as for Problem 2

I was able to load the stock VDL sounds using the built in Sound Set and get my score to load up and playback.  I did get the ";File not Found"; window a couple times but I figured it was because I wrote in VDL 5.2.5 Sound Set.  It played the sounds it did have, and I can work for now but still no sound sets.