No doubt, Vista was intended to be pretty! But as in real life so it is with operating systems, Pretty comes at a price and that price is your system's resources! Even if your system seems to be running fine, you may decided you don't need so much pretty and can go without Vista's thumbnail icons.
Thumbnails are mini graphical representations of a file. This is great if you need to scroll through a large batch of images as it lets you see the image without having to actually open the file. Unfortunately, graphic files take longer to open therefore having the feature turned on if your system isn't fully equipped to handle Vista can really reduce overall performance. So, what to do... just disable this feature so that the files look like files and not pretty lil pictures!
Click the following...
Start ->
Control Panel ->
Folder Options ->
View Tab
To disable the thumbnail feature just check the box under under Files and Folders which reads
Always show icons, never thumbnails 
Linear Mode
