In the old days people used shelves and tables with computers on them all wired up to the internet. This was common for web servers before machines became powerful enough to be consolidated. As network moved from 10 megabit to 100 megabit it was now possible to run games with remote desktop as easily as managing a server.
Given game compatibility problems, it clear how a rack mounted setup can be considered. Low cost 4U chassis are very low cost but the rack itself is expensive because its very heavy. We have seen vast numbers of modesks of rack mounted chassis in the market. Most have 4-6 hard disk bays. Extra hard disks can be shared easily over the LAN. Same applies for CD and DVD drives.
Now with a dozen or more machines with various video cards and even SLI or CFX configurations, real game testing is now possible. Each can be connected to by remote desktop.
It’s possible to use a machine with lots of hard disks for backups and network storage. Windows explorer can show hundreds of machines easily.
When several machines are being using on a large network, remember to use a suitable naming scheme so that each machine is easily found.
By default Windows XP does not use a very easily identified network ID so its important to change it so it can be more readily discovered. For example, XP-AMD6970 and XP-GTX260 are much more identifiable than WINDOWS82M12QWM.
Vista and above are as bad as XP for default network names so its important to make them easier to identify.
Even the home versions of windows have a client to connect to the remote machines. The home versions are only unable to be a host. A laptop can actually stream games from a wide number of rack mounted machines as needed and all can be used for testing games etc.