If you are tinkering with VMWare on OS X

then a few links to save you a little googling. If you wanna use some of the public VMWAre images such as Ubuntu 7.10 desktop then you might wanna use BitTorrent to download it, then to unpack the RAR file try UnRarX. I've found the nicest way to use VMWare on Leopard is to run each VM image in a separate Space in full screen mode which is pretty neat...