I've used Macs for a long time and there are a lot of reasons I generally prefer them. Spaces is not one. For the first time since I started using macs (a '85 vintage Mac 512K): a removed an OS upgrade.

Spaces is not a virtual desktop manager; it's an application manager. Virtual Desktop applications --when done right-- allow you to organize things not by application but by project or task. If I need to have a browser window open for general browsing on one virtual desktop and another open to test what I'm developing on that virtual desktop, a good virtual desktop manager can handle that.

Virtual Desktoop Managers don't force you to switch to another desktop just because you clicked on an icon in the dock (hey... where'd I go?!? I just want the app in front so I can open a new window you stupid OS).

If you like Spaces fine, but it's not a virtual desktop manager. It's in a special category of its own. If someone can figure out how to hack Spaces it can be reconfigured to run as a virtual desktop manager, great. Until then, this product seems to work great (granted I'm testing it under 10.4), allows me to do what I want _and_ allows me to re-upgrade to 10.5.