Okay - I kind of found a way to do this, but it does not work with the taskbar vertical (or I haven't got it to work yet, pretty sure it won't anyways with this method).
A while back I wanted to get my icons centered like a Macs, so I followed this tutorial. It works perfect, and your taskbar stays centered that way (minus when you open new windows, they show up to the right of center). Your taskar should look similar to this:
After you have finished that tutorial, instead of locking the taskbar, drag it up one more space so it is two units high. After that, take the little scroll thing on the notification area side and drag that over until your icons are stacked like you want them, similar to this
:
Alternatively, you could add another folder on the other side of your icons and use that to adjust the stacking of the icons instead of the notification area, incase you like it in a certain way.
Now, if you want a vertical taskbar with programs or files, first unlock the taskbar and drag it to the side of the screen you would like for it to be on. Second, create some folders, that contain the items that you want to be stacked on the bar. For example, I just used Folder and then duplicated it to get Folder2 (that's why the two columns match) - unfortunately, I haven't found out how to make the taskbar icons multi layered yet (You can put an application in the folder, and it will launch, but it will then show up as the last icon in the task bar, and won't actually be a taskbar icon - I hope that makes sense.) I'll post back here if I can find a way to fix that - but anyways, this is what mine looked like.
1)Make a shortcut to Wscript.exe
2)Set the target adding the vbs file as a parameter
e.g. c:\windows\system32\wscript.exe c:\blah\a.vbs
3)Drag the shortcut onto the taskbar.
You could change the icon between steps 2 and 3, or after step 3.
You can drag multiple on, but you must ensure that you change the target of the shortcut.
If you tried to drag the vbs file itself onto the taskbar you should find it won't work but the above method should work
If you try to drag the exe itself, it's a bit of an issue 'cos you're not changing the target of the shortcut. And anyhow since dragging makes a shortcut anyway, it makes sense to drag a shortcut.
You can see the path to these pinned shortcuts here (change username accordingly)
C:\Users\name\AppData\Roaming\Microsoft\Internet Explorer\Quick Launch\User Pinned\TaskBar
And you can get that path by shift right clicking a pinned icon after all its windows are closed, and you get a menu with properties which is the shortcut properties, and in the general tab you see the location of the lnk file - the directory it's in being that one I mentioned.
Best Answer
You can either right click the desktop and Personalize, then choose an Aero theme, or there is an Aero troubleshooting tool under Control Panel\All Control Panel Items\Troubleshooting -> "Display Aero desktop effects" (can be slow to load)