Well, the easiest customization is obviously the wallpaper
Docks can really change the flow of your desktop as well, if you're into that kind of task management.
It's start getting a bit more complicated with Visual styles and icons; however, visual styles act as a powerful source of custom material, so I'd definitely look into it.
To be honest I'm not too familiar with how to install visual styles on Vista since I never used it, but I know there are tutorials online.
Blackbox is pretty minimal isn't it?
I think it would be a nice choice for something like a netbook.
thanks for the info middy, i was just thinking i wanna tune up my desktop on my way home cause i just formatted my other laptop and boom u guys stroke up a convo on this subject here