Yes, that is possible, but if you do that, probably all icons will be changed.
The setting that looks most like Vista's Icons is Thumbnail. So if you can view the image on your desktop as a thumbnail, than it should be ok.
Download Vista Folders here:
http://monolistic.deviantart.com/art/Vista...ders-3-44410063
Change the icons to the ones you just downloaded.
How to change the icons size:
Right Click Desktop + Choose “Properties”
In the Properties Window click on the “Appearance Tab” at the top.
In the Appearance Window click on the button called “Advanced”
In the Advanced Appearance Window choose “Item:” from the drop down list and choose “Icon” and you can choose desired Icon size. By default many users will see 32 x 32 pixels but this can be changed to whatever you want.
And this here is a guide to change the Icons to thumbnails. that is more vista-like then the normal setting.
Btw, if you have Tune Up utilities, use that for resizing the icons. Its way better. Mainly because you can select "default size" and all that. It also changes the shortcut icon.
if you have any questions, just ask.